Semiconductor device and method of manufacturing the same

ABSTRACT

In an LCD driver, in a high voltage resistant MISFET, end portions of a gate electrode run onto electric field relaxing insulation regions. Wires to become source wires or drain wires are formed on an interlayer insulation film of the first layer over the high voltage resistant MISFET. At this moment, when a distance from an interface between a semiconductor substrate and a gate insulation film to an upper portion of the gate electrode is defined as “a”, and a distance from the upper portion of the gate electrode to an upper portion of the interlayer insulation film on which the wires are formed is defined as “b”, a relation of a&gt;b is established. In such a high voltage resistant MISFET structured in this manner, the wires are arranged so as not to be overlapped planarly with the gate electrode of the high voltage resistant MISFET.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority from Japanese Patent ApplicationNo. JP 2007-153840 filed on. Jun. 11, 2007, and No. JP 2008-71291 filedon Mar. 19, 2008, the content of which is hereby incorporated byreference into this application.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a semiconductor device and a method ofmanufacturing the same, and particularly, it relates to an effectivetechnology when applied to a semiconductor device equipped with arelatively high voltage resistant MISFET such as a Liquid CrystalDisplay (LCD) driver and the like and a method of manufacturing thesame.

BACKGROUND OF THE INVENTION

In Japanese Patent Application Laid-Open Publication No. 2005-116744(Patent Document 1), a technology of forming a high voltage resistanttransistor and a low voltage resistant transistor on a same substrate isdescribed. In this Patent Document 1, it is said that the high voltageresistant transistor has an offset insulating layer for relaxing anelectric field. A guard ring formed in the high voltage resistanttransistor formation region is connected to a wire (a wire of the lowestlayer) formed on an interlayer insulation film of the first layer. Incontrast, a source region or a drain region of the high voltageresistant transistor is connected to a wire (not the wire of the lowestlayer) formed on an interlayer insulation film of a second layer. Inother words, the source region or the drain region of the high voltageresistant transistor is connected to a wire arranged on the interlayerinsulation film of the second layer by a plug that penetrates both theinterlayer insulation film of the first layer and the interlayerinsulation film of the second layer at once.

In Japanese Patent Application Laid-Open Publication No. 4-171938(Patent Document 2), a technology of forming a high voltage resistantn-channel FET and a low voltage resistant n-channel FET on a samesubstrate is described. In this Patent Document 2, in the low voltageresistant n-channel FET, a source region or a drain region thereof isconnected to a wire of the lowest layer formed on an interlayerinsulation film of the first layer. In contrast, in the high voltageresistant n-channel FET, a source region or a drain region thereof isconnected to, not the wire of the lowest layer, but a wire formed on aninterlayer insulation film of a second layer.

SUMMARY OF THE INVENTION

In recent years, the LCD that uses liquid crystal as a display elementhas been spreading rapidly. This LCD is controlled by a driver to drivethe LCD. The LCD driver is configured with a semiconductor chip, and itis mounted on, for example, a glass substrate. The semiconductor chipconfiguring the LCD driver has a structure in which a plurality oftransistors and multilayer wirings are formed over a semiconductorsubstrate, and a bump electrode is formed on the surface. Thesemiconductor chip is mounted on the glass substrate via the bumpelectrode formed on the surface.

In the plurality of transistors (MISFETs) formed in the LCD driver,there are low voltage resistant MISFETs and high voltage resistantMISFETs. That is, in the LCD driver, there are usually a logic circuitconfigured with a low voltage resistant MISFET drove at a voltage ofapproximately 5 V, and a circuit that applying a voltage ofapproximately 20 V to 30 V to the electrode of the LCD. In order toapply the voltage of approximately 20 V to 30 V to the electrode of theLCD, a level shift circuit is connected to the logic circuit drove at avoltage of approximately 5 V, and a switching element is connectedthereto via the level shift circuit. This switching element isconfigured with an MISFET drove at a voltage of 20 V to 30 V, so calledas a high voltage resistant MISFET.

As described above, the LCD driver comprises a low voltage resistantMISFET and a high voltage resistant MISFET on the same semiconductorsubstrate. An interlayer insulation film is formed on the low voltageresistant MISFET and the high voltage resistant MISFET formed on thesame semiconductor substrate, and wires are formed on this interlayerinsulation film. The wires and the MISFETs are connected by a plugpenetrating the interlayer insulation film. Generally, the wireconnecting to a source region or a drain region of the high voltageresistant MISFET is not formed on an interlayer insulation film of afirst layer, but is formed on an interlayer insulation film of a secondlayer which is further formed on the interlayer insulation film of thefirst layer. In other words, since in the high voltage resistant MISFET,a relatively high voltage of approximately 20 V to 30 V is used, inorder to secure voltage resistance between the wire and the high voltageresistant MISFET (gate electrode), the wire is not arranged on theinterlayer insulation film of the first layer, but the wire is arrangedon the interlayer insulation film of the second layer to secure thevoltage resistance of the high voltage resistant MISFET. Therefore, thehigh voltage resistant MISFET and the wire are connected via a plugpenetrating the interlayer insulation film of the first layer, andsuccessively, via a plug penetrating the interlayer insulation film ofthe second layer.

In recent years, miniaturization of the LCD driver is demanded. For thispurpose, a diameter of the plug (contact plug) to connect the MISFET andthe wire of the LCD driver is reduced. For example, concretely, thediameter of the plug is largely reduced to 0.24 μm or 0.14 μm. However,when the diameter of the plug is reduced, a problem that the resistanceof the plug becomes large conspicuously occurs. In particular, in thehigh voltage resistant MISFET, since the high voltage resistant MISFETand the wire are connected each other by the plug penetrating both theinterlayer insulation film of the first layer and the interlayerinsulation film of the second layer, when the diameter of the plug isreduced, an aspect ratio of the plug becomes large and the resistanceincreases. Therefore, in the LCD driver, the wire is formed on theinterlayer insulation film of the first layer, and a wire width of thewire formed on the interlayer insulation film of the first layer is madewide and the number of plugs to connect the interlayer insulation filmof the first layer and the interlayer insulation film of the secondlayer is increased, whereby the low resistance of the plug is secured.By forming the wire on the interlayer insulation film of the firstlayer, there is no need to directly connect the plug penetrating theinterlayer insulation film of the first layer and the plug thatpenetrates the interlayer insulation film of the second layer, so thatthe aspect ratio of the plug can be reduced. Therefore, the highresistance due to reduction of the plug diameter can be suppressed.

Further, by thinning a film thickness of the interlayer insulation filmof the first layer, the aspect ratio of the plug formed in theinterlayer insulation film of the first layer is made small. In thismanner, in chip shrinking of the LCD driver, the film thickness of theinterlayer insulation film of the first layer is made thin, and the wireis formed on the interlayer insulation film of the first layer. The wirewidth of the wire formed on the interlayer insulation film of the firstlayer is made wide, and the number of plugs to connect the interlayerinsulation film of the first layer and the interlayer insulation film ofthe second layer is increased. Since the wire width of the wire formedon the interlayer insulation film of the first layer is made wide, asource wire to be connected to the source region of the high voltageresistant MISFET or a drain wire to be connected to the drain area ofthe high voltage resistant MISFET is formed so as to have a region whichis planarly overlapped with the gate electrode of the high voltageresistant MISFET.

In this manner, the high resistance of the plug with the miniaturizationof the LCD driver can be restrained, but another problem newly occurs.In other words, since the film thickness of the interlayer insulationfilm of the first layer is made thin, and the LCD driver is configuredso that the source wire and the drain wire and the gate electrode of thehigh voltage resistant MISFET should be overlapped planarly, voltageresistance failures occur between the gate electrode of the high voltageresistant MISFET and the source wire, or between the gate electrode ofthe high voltage resistant MISFET and the drain region. As causes of anoccurrence of the voltage resistance failure, firstly, there is the factthat the interlayer insulation film of the first layer to be formed onthe gate electrode of the high voltage resistant MISFET tends to becomeextremely thin due to variation in the film formation step of theinterlayer insulation film of the first layer and the polishing step byChemical Mechanical Polishing (CMP) and the like. For this fact, it isconsidered that the voltage resistance failure occurs between the gateelectrode and the source wire or the drain wire formed on the interlayerinsulation film of the first layer.

As the second cause, there is the fact that, in the high voltageresistant MISFET, the film thickness of the gate insulation film isthick. In the high voltage resistant MISFET, an electric field relaxinginsulation region protruding slightly from the semiconductor substrateis formed in the source region or the drain region; an end portion ofthe gate electrode runs onto this electric field relaxing insulationregion; and accordingly, the height of the gate electrode is higher thanthat of the low voltage resistant MISFET.

Further, as the third cause, there is the fact that a drive voltage ofthe high voltage resistant MISFET is approximately 20 V to 30 V, and ishigher than that of the low voltage resistant MISFET. From the facts, inthe structure of the present LCD driver, it is understood that it isdifficult to realize both of suppressing the high resistance of the plugdue to the size reduction and of improving the voltage resistancefailure between the gate electrode of the high voltage resistant MISFETand the wire at the same time.

The object of the present invention is to provide a technology tosuppress the high resistance of the plug due to the miniaturization in asemiconductor device comprising the high voltage resistant MISFET andthe low voltage resistant MISFET such as the LCD driver and the like,and to improve the voltage resistance failure between the gate electrodeof the high voltage MISFET and the wire.

The above and other objects and novel characteristics of the presentinvention will be apparent from the description of this specificationand the accompanying drawings.

The typical ones of the inventions disclosed in this application will bebriefly described as follows.

A semiconductor device according to the present invention comprises:(a1) a gate insulation film formed on a semiconductor substrate; (a2) agate electrode formed on the gate insulation film; (a3) a MISFET havinga source region and a drain region to align with the gate electrode; (b)an insulation film formed over the MISFET; (c) a first plug penetratingthe insulation film and electrically connected to the source region; and(d) a second plug penetrating the insulation film and electricallyconnected to the drain region. The semiconductor device furthercomprises: (e) a source wire formed over the insulation film andelectrically connected to the first plug; and (f) a drain wire formed onthe insulation film and electrically connected to the second plug.Herein, when a distance from an interface between the semiconductorsubstrate and the gate insulation film to an upper surface of the gateelectrode is defined as “a”, and a distance from the upper surface ofthe gate electrode to an upper portion of the insulation film on whichthe source wire and the drain wire are formed is defined as “b”, arelation of a>b is established. At this time, the semiconductor deviceis characterized by that the gate electrode and the source wire arearranged not to be overlapped planarly with each other, and the gateelectrode and the drain wire are arranged not to be overlapped planarlywith each other.

In addition, a method of manufacturing a semiconductor device accordingto the present invention comprises the steps of: (a) forming an elementisolation region and an electric field relaxing insulation region in asemiconductor substrate; (b) forming a gate insulation film over thesemiconductor substrate; and (c) forming a pair of low concentrationimpurity diffusion regions so that each of the impurity regions containsthe electric field relaxing insulation region. The method furthercomprises the steps of: (d) forming a gate electrode over the gateinsulation film; and (e) forming a side-wall on a side wall of bothsides of the gate electrode. The method further includes the step of (f)forming a pair of high concentration impurity diffusion regions in eachregion contained in the pair of low concentration impurity diffusionregions and existing outside the electric field relaxing insulationregion, and forming a source region configured with one of the pair oflow concentration impurity diffusion regions and one of the pair of highconcentration impurity diffusion regions included therein, and a drainregion configured with the other one of the pair of low concentrationimpurity diffusion regions, and the other one of the pair of highconcentration impurity diffusion regions included therein. The methodfurther comprises the steps of: (g) forming an insulation film so as tocover the gate electrode; and (h) forming a first plug penetrating theinsulation film and reaching the source region, and a second plugpenetrating the insulation film and reaching the drain region. Themethod further comprises the step of (i) forming a source wire connectedto the first plug over the insulation film, and a drain wire connectedto the second plug over the insulation film. Herein, when a distancefrom an interface between the semiconductor substrate and the gateinsulation film to an upper portion of the gate electrode is defined as“a”, and a distance from the upper portion of the gate electrode to anupper surface of the insulation film on which the source wire and thedrain wire are formed is defined as “b”, a relation of a>b isestablished. In this situation, the method is characterized by that thegate electrode and the source wire are formed not to be overlappedplanarly with each other, and the gate electrode and the drain wire areformed not to be overlapped planarly with each other.

The effects obtained by typical aspects of the present invention will bebriefly described below.

In a semiconductor device comprising the high voltage resistant MISFETand the low voltage resistant MISFET such as the LCD driver and thelike, it is possible to suppress the high resistance of the plug due tothe miniaturization of a semiconductor device, and to improve thevoltage resistance failure between the gate electrode of the highvoltage resistant MISFET and the wire.

BRIEF DESCRIPTIONS OF THE DRAWINGS

FIG. 1 is a plan view showing a semiconductor chip (LCD driver)according to an embodiment of the present invention;

FIG. 2 is a cross sectional view showing an example of an internalstructure of the semiconductor chip shown in FIG. 1;

FIG. 3 is a plan view of the high voltage resistant MISFET shown in FIG.2;

FIG. 4 is a cross sectional view showing a step of manufacturing asemiconductor device according to the present embodiment;

FIG. 5 is a cross sectional view showing a step of manufacturing thesemiconductor device continued from FIG. 4;

FIG. 6 is a cross sectional view showing a step of manufacturing thesemiconductor device continued from FIG. 5;

FIG. 7 is a cross sectional view showing a step of manufacturing thesemiconductor device continued from FIG. 6;

FIG. 8 is a cross sectional view showing a step of manufacturing thesemiconductor device continued from FIG. 7;

FIG. 9 is a cross sectional view showing a step of manufacturing thesemiconductor device continued from FIG. 8;

FIG. 10 is a cross sectional view showing a step of manufacturing thesemiconductor device continued from FIG. 9;

FIG. 11 is a cross sectional view showing a step of manufacturing thesemiconductor device continued from FIG. 10;

FIG. 12 is a cross sectional view showing a step of manufacturing thesemiconductor device continued from FIG. 11;

FIG. 13 is a cross sectional view showing a step of manufacturing thesemiconductor device continued from FIG. 12;

FIG. 14 is a cross sectional view showing a step of manufacturing thesemiconductor device continued from FIG. 13;

FIG. 15 is a cross sectional view showing a step of manufacturing thesemiconductor device continued from FIG. 14;

FIG. 16 is a cross sectional view showing a step of manufacturing thesemiconductor device continued from FIG. 15;

FIG. 17 is a cross sectional view showing a step of manufacturing thesemiconductor device continued from FIG. 16;

FIG. 18 is a cross sectional view showing a step of manufacturing thesemiconductor device continued from FIG. 17;

FIG. 19 is a cross sectional view showing a step of manufacturing thesemiconductor device continued from FIG. 18;

FIG. 20 is a cross sectional view showing a step of manufacturing thesemiconductor device continued from FIG. 19;

FIG. 21 is a cross sectional view showing a step of manufacturing thesemiconductor device continued from FIG. 20;

FIG. 22 is a cross sectional view showing a step of manufacturing thesemiconductor device continued from FIG. 21;

FIG. 23 is a cross sectional view showing a step of manufacturing thesemiconductor device continued from FIG. 22;

FIG. 24 is a cross sectional view showing a step of manufacturing thesemiconductor device continued from FIG. 23;

FIG. 25 is a cross sectional view showing a step of manufacturing thesemiconductor device continued from FIG. 24;

FIG. 26 is a cross sectional view showing a situation in which asemiconductor chips is mounted on a glass substrate;

FIG. 27 is a figure showing an entire structure of a LCD;

FIG. 28 is a cross sectional view showing semiconductor devicesaccording to a second embodiment and a third embodiment;

FIG. 29 is a table concretely showing a dimensional error of a patternin the photolithography process and a stack gap between patterns;

FIG. 30 is a plane view showing a structure of a resistance elementaccording to a fourth embodiment;

FIG. 31 is a cross sectional view including a cross section at B-B linein FIG. 30;

FIG. 32 is a cross sectional view showing a step of forming a generalelement isolation region;

FIG. 33 is a cross sectional view showing a step of forming the generalelement isolation region continued from FIG. 32;

FIG. 34 is a cross sectional view showing a state in which etchingremain is left due to a foreign matter upon forming an element isolationtrench;

FIG. 35 is a cross sectional view showing a step of forming the elementisolation region continued from FIG. 34;

FIG. 36 is a cross sectional view showing an example of forming aresistance element via a thin gate insulation film over the elementisolation region on which the etching remain is formed;

FIG. 37 is a cross sectional view showing an example of forming aresistance element via a thick gate insulation film over the elementisolation region on which the etching remain is formed;

FIG. 38 is a cross sectional view showing a step of manufacturing asemiconductor device according to a fifth embodiment;

FIG. 39 is a cross sectional view showing a step of manufacturing thesemiconductor device continued from FIG. 38;

FIG. 40 is a cross sectional view showing a step of manufacturing thesemiconductor device continued from FIG. 39;

FIG. 41 is a cross sectional view showing a step of manufacturing thesemiconductor device continued from FIG. 40;

FIG. 42 is a cross sectional view showing a step of manufacturing thesemiconductor device continued from FIG. 41;

FIG. 43 is a cross sectional view showing a step of manufacturing thesemiconductor device continued from FIG. 42; and

FIG. 44 is a cross sectional view showing a step of manufacturing thesemiconductor device continued from FIG. 43.

DESCRIPTIONS OF THE PREFERRED EMBODIMENTS

In the embodiments described below, the invention will be described in aplurality of sections or embodiments when required as a matter ofconvenience. However, these sections or embodiments are not irrelevantto each other unless otherwise stated, and the one relates to the entireor a part of the other as a modification example, details, or asupplementary explanation thereof.

Also, in the embodiments described below, when referring to the numberof elements (including number of pieces, values, amount, range, and thelike), the number of the elements is not limited to a specific numberunless otherwise stated or except the case where the number isapparently limited to a specific number in principle. The number largeror smaller than the specified number is also applicable.

Further, in the embodiments described below, it goes without saying thatthe components (including element steps) are not always indispensableunless otherwise stated or except the case where the components areapparently indispensable in principle.

Similarly, in the embodiments described below, when the shape of thecomponents, positional relation thereof, and the like are mentioned, thesubstantially approximate and similar shapes and the like are includedtherein unless otherwise stated or except the case where it can beconceived that they are apparently excluded in principle. The same goesfor the numerical value and the range described above.

Also, components having the same function are denoted by the samereference symbols throughout the drawings for describing theembodiments, and the repetitive description thereof is omitted. Also,hatching is used even in a plan view so as to make the drawings easy tosee.

First Embodiment

First, a semiconductor chip for an LCD driver according to the presentembodiment will be explained. FIG. 1 is a plan view showing a structureof a semiconductor chip CHP (semiconductor device) according to thepresent embodiment. The semiconductor chip CHP according to the presentembodiment is an LCD driver. In FIG. 1, the semiconductor chip CHP has asemiconductor substrate 1S formed into, for example, an elongatedrectangle shape, and the LCD driver to drive, for example, a liquidcrystal display device is formed on a main surface of the semiconductorsubstrate 1S. This LCD driver has a function to supply a voltage to eachpixel of cell arrays constituting the LCD and control directions ofliquid crystal molecules, and includes gate drive circuits C1, a sourcedrive circuit C2, a liquid crystal drive circuit C3, graphic RandomAccess Memories (RAM) C4 and peripheral circuits C5.

In the vicinity of the outer circumference of the semiconductor chipCHP, a plurality of bump electrodes BMP are arranged along an outercircumference of the semiconductor chip CHP at specified intervals. Theplurality of bump electrodes BMP are arranged on an active region onwhich elements and wires of semiconductor chip CHP are formed. In theplurality of bump electrodes BMP, there are bump electrodes forintegrated circuits that are necessary for a structure of the integratedcircuit, and dummy bump electrodes that are not necessary for thestructure of the integrated circuit. In the vicinities of one long sideand two short sides of the semiconductor chip CHP, the bump electrodesBMP are arranged in a zigzag shape. The plurality of bump electrodes BMParranged in a zigzag shaped are mainly bump electrodes for gate outputsignals or source output signals. The bump electrodes BMP arranged in azigzag shape at a center in the long side of the semiconductor chip CHPare bump electrodes for the source output signals, and the bumpelectrodes BMP arranged in a zigzag shape in the vicinities of bothcorners of the long side of the semiconductor chip CHP and both theshort sides of the semiconductor chip CHP are bump electrodes for thegate output signals. By adopting such a zigzag arrangement, it ispossible to arrange the bump electrodes BMP for the gate output signalsand the bump electrodes BMP of the source output signals that need manynumbers, while suppressing increase of the size of the semiconductorchip CHP. In other words, it is possible to increase the number of thebump electrodes while reducing the chip size.

In addition, in the vicinity of the other long side of the semiconductorchip CHP, bump electrodes BMP are arranged in a straight linearrangement rather than in the zigzag arrangement. The bump electrodesBMP arranged in the straight line arrangement are bump electrodes BMPfor digital input signals or analog input signals. Further, in thevicinity of the four corners of the semiconductor chip CHP, dummy bumpelectrodes are formed. Note that, in FIG. 1, the example where the bumpelectrodes BMP for the gate output signals or source output signals arearranged in the zigzag arrangement and the bump electrodes BMP for thedigital input signals or the analog input signals are arranged in thestraight line arrangement is described. However, it is also possible tomake a structure where the bump electrodes BMP for the gate outputsignals or source output signals are arranged in straight linearrangement, and the bump electrodes BMP for the digital input signalsor analog input signals are arranged in the zigzag arrangement.

As for external dimensions of the semiconductor chip CHP, there are, forexample, a chip whose length in the short side direction is 1.0 mm, anda length in the long side direction is 12.0 mm, and another chip whoselength in the short side direction is 1.0 mm, and a length in the longside direction is 10.0 mm. Furthermore, there is, for example, stillanother chip whose length in the short side direction is 2.0 mm, and alength in the long side direction is 20.0 mm. The semiconductor chip CHPthat is used in the LCD driver is in the rectangle shape asabove-mentioned. Concretely, there are many chips whose ratio of thelength of the short side to the length of the long side is 1:8 to 1:12.Furthermore, there are chips whose length in the long side direction is5 mm or more.

In the inside of the semiconductor chip CHP being the LCD driverconfigured as shown in FIG. 1, there are low voltage resistant MISFETsused for the logic circuits, and high voltage resistant MISFETs used forthe liquid crystal drive circuits and the like. For example, in thepresent specification, a MISFET working at a drive voltage ofapproximately 5 V to 6 V is referred to as a low voltage resistantMISFET, and a MISFET working at a drive voltage of approximately 20 V to30 V is referred to as a high voltage resistant MISFET.

FIG. 2 is a cross sectional view of a MISFET existing inside thesemiconductor chip CHP shown in FIG. 1. In FIG. 2, the low voltageresistant MISFET and the high voltage resistant MISFET are shown.

First, a structure of the high voltage resistant MISFET will beexplained. In FIG. 2, in the high voltage resistant MISFET formationregion, element isolation regions 2 are formed over a semiconductorsubstrate 1S. In other words, the high voltage resistant MISFET isformed in an active regions isolated by the element isolation regions 2.In the inside of the semiconductor substrate 1S sandwiched between theplurality of element isolation regions 2, a p-type well 4 is formed.This p-type well 4 is a well formed for the high voltage resistantMISFET. Furthermore, in the high voltage resistant MISFET formationregion, electric field relaxing insulation regions 3 are formed inregions sandwiched between the plurality of element isolation regions 2.The electric field relaxing insulation regions 3 have, for example, thesame structure of the element isolation regions 2, and are formed by theShallow Trench Isolation (STI) method.

In the inside of the p-type well 4, a pair of high voltage resistant lowconcentration impurity diffusion regions (n-type semiconductor regions)6 are formed, and each of the high voltage resistant low concentrationimpurity diffusion regions is formed so as to contain the electric fieldrelaxing insulation region 3. On the surface of the semiconductorsubstrate 1S between the pair of high voltage resistant lowconcentration impurity diffusion regions 6, a gate insulation film 8 isformed, and a gate electrode 10 b is formed over this gate insulationfilm 8. The gate insulation film 8 is formed with, for example, asilicon oxide film, and the gate electrode 10 b is formed with, forexample, a stacked film of a polysilicon film and a cobalt silicidefilm. By forming the cobalt silicide film on the polysilicon film as thegate electrode 10 b, it is possible to realize the low resistance of thegate electrode 10 b.

The gate insulation film 8 is formed so that the end portions thereofrun onto the electric field relaxing insulation regions 3. In otherwords, in the high voltage resistant MISFET formation region, sinceoccupancy of the element isolation regions 2 and the electric fieldrelaxing insulation regions 3 becomes high, the element isolationregions 2 and the electric field relaxing insulation regions 3 tend toprotrude from the surface of the semiconductor substrate 1S. Therefore,the end portions of the gate insulation film 8 are shaped so as to runonto the electric field relaxing insulation regions 3. Accordingly, asfor the gate electrode 10 b formed on the gate insulation film 8, theend portions thereof are formed so as to swell.

Next, side walls 12 are formed on side walls of both sides of the gateelectrode 10 b, and these side walls 12 are also formed over theelectric field relaxing insulation regions 3. Outside the electric fieldrelaxing insulation regions 3 and inside high voltage resistant lowconcentration impurity diffusion regions 6, high voltage resistant highconcentration impurity diffusion regions (n-type semiconductor regions)14 are formed. On the surface of this high voltage resistant highconcentration impurity diffusion region 14, a cobalt silicide film 15 isformed. As described above, the source region of the high voltageresistant MISFET is formed with one of a pair of the high voltageresistant low concentration impurity diffusion region 6, the highvoltage resistant high concentration impurity diffusion region 14 formedinside this high voltage resistant low concentration impurity diffusionregion 6, and the cobalt silicide film 15. In the same manner, the drainregion of the high voltage resistant MISFET is formed with the other oneof the pair of the high voltage resistant low concentration impuritydiffusion region 6, the high voltage resistant high concentrationimpurity diffusion region 14 formed inside this high voltage resistantlow concentration impurity diffusion region 6, and the cobalt silicidefilm 15.

In the present embodiment, since the electric field relaxing insulationregions 3 are formed at the end portions of the gate electrode 10 b, theelectric field formed under the end portions of the gate electrode 10 bcan be relaxed. Therefore, it is possible to secure voltage resistancebetween the gate electrode 10 b and the source region or between thegate electrode 10 b and the drain region. In other words, in the highvoltage resistant MISFET, by forming the electric field relaxinginsulation regions 3, it is possible to secure the voltage resistanceeven if a drive voltage becomes 20 V to 30 V.

The high voltage resistant MISFET according to the present embodiment isconfigured as mentioned above, and hereinafter, a structure of the lowvoltage resistant MISFET in the present embodiment will be explained.

In FIG. 2, in the low voltage resistant MISFET formation region, elementisolation regions 2 are formed over the semiconductor substrate 1S. Inother words, a low voltage resistant MISFET is formed in the activeregion isolated by the element isolation regions 2. A p-type well 4 isformed inside the semiconductor substrate 1S sandwiched between theplurality of element isolation regions 2. In the p-type well 4, a p-typewell 5 that is a well for the low voltage resistant MISFET is formed.Incidentally, the electric field relaxing insulation region 3 is notformed in the low voltage resistant MISFET formation region.

A gate insulation film 7 is formed on the p-type well 5, and a gateelectrode 10 a is formed on this gate insulation film 7. The gateinsulation film 7 is formed with, for example, a silicon oxide film. Thegate electrode 10 a is formed with, for example, a stacked film of apolysilicon film and a cobalt silicide film. By forming the cobaltsilicide film on the polysilicon film as the gate electrode 10 a, it ispossible to realize low resistance of the gate electrode 10 a. In thelow voltage resistant MISFET, since a drive voltage is lower than thatof the high voltage resistant MISFET, a film thicknesses of the gateinsulation film 7 of the low voltage resistant MISFET is thinner thanthat of the gate insulation film 8 of the high voltage resistant MISFET.

Side walls 12 are formed on side walls of both sides of the gateelectrode 10 a, and a pair of low voltage resistant low concentrationimpurity diffusion regions (n-type semiconductor regions) 11 is formedimmediately under this side walls 12 in the p-type well 5. Low voltageresistant high concentration impurity diffusion regions 13 (n-typesemiconductor regions) are formed outside the pair of low voltageresistant low concentration impurity diffusion regions 11. On thesurface of this low voltage resistant high concentration impuritydiffusion region 13, the cobalt silicide film 15 is formed. As describedabove, a source region of the low voltage resistant MISFET is formedwith one of the low voltage resistant low concentration impuritydiffusion regions 11, the low voltage resistant high concentrationimpurity diffusion region 13 formed outside this low voltage resistantlow concentration impurity diffusion region 11, and the cobalt silicidefilm 15 formed on the surface of the low voltage resistant highconcentration impurity diffusion region 13. In the same manner, a drainregion of the low voltage resistant MISFET is formed with the other oneof the low voltage resistant low concentration impurity diffusionregions 11, the low voltage resistant high concentration impuritydiffusion region 13 formed outside this low voltage resistant lowconcentration impurity diffusion region 11, and the cobalt silicide film15 formed on the surface of the low voltage resistant high concentrationimpurity diffusion region 13. As mentioned above, the low voltageresistant MISFET is configured.

Next, a wiring structure formed over the high voltage resistant MISFETand the low voltage resistant MISFET will be explained. In the presentembodiment, the wiring structure formed over the high voltage resistantMISFET has one of the characteristics thereof. First, the wiringstructure on the high voltage resistant MISFET that is a characteristicof the present embodiment will be explained.

As shown in FIG. 2, an interlayer insulation film of the first layer isformed on the high voltage resistant MISFET. Concretely, the interlayerinsulation film of the first layer is formed with a stacked film of asilicon nitride film 16 and a silicon oxide film 17. In the interlayerinsulation film of the first layer made of the silicon nitride film 16and the silicon oxide film 17, a plug (first plug) PLG1 penetrating thisinterlayer insulation film and reaching the source region of the highvoltage resistant MISFET, and a plug (second plug) PLG1 penetrating thisinterlayer insulation film and reaching the drain region of the highvoltage resistant MISFET are formed. On the interlayer insulation filmof the first layer on which the plug PLG1 is formed, wires (source wireand drain wire) HL1 are formed. The wires HL1 are formed on theinterlayer insulation film of the first layer, but further, aninterlayer insulation film of the second layer and an interlayerinsulation film of the third layer are formed over the interlayerinsulation film of the first layer including the wires HL1, and wiresare formed on the respective interlayer insulation films. In otherwords, multilayer wirings are formed on the high voltage resistantMISFET, but in FIG. 2, only the first layer wires HL1 that is thecharacteristic of the present invention are shown.

One of the characteristics of the present embodiment is that the wiresHL1 to become the source wires and the drain wires are formed on theinterlayer insulation film of the first layer, and the wires HL1 arearranged so that the wires HL1 and the gate electrode 10 b of the highvoltage resistant MISFET should not be overlapped planarly.

In the conventional LCD driver, in the high voltage resistant MISFETformation region, wires are not formed on the interlayer insulation filmof the first layer, but formed on the interlayer insulation film of thesecond layer for the first time. This is made from the viewpoint tosecure the voltage resistance between the gate electrode of the highvoltage resistant MISFET and the source wire or the voltage resistancebetween the gate electrode of the high voltage resistant MISFET and thedrain wire. In this case, with the plug penetrating two kinds of theinterlayer insulation films which are the interlayer insulation film ofthe first layer and the interlayer insulation film of the second layer,the source wire and the source region of the high voltage resistantMISFET or the drain wire and the drain region of the high voltageresistant MISFET are connected. Therefore, there is a concern that theresistance may increase due to the plug penetrating the interlayerinsulation of the first layer and the interlayer insulation film of thesecond layer, but the diameter (for example, 0.24 μm) of the plug hasbeen relatively secured, and accordingly, the resistance of the plug hasnot been so conspicuous as a problem.

However, the diameter of the plug has been largely reduced along withminiaturization of the LCD driver. For example, the plug diameter of0.24 μm has been reduced to the plug diameter of 0.14 μm. In this case,with the plug penetrating both of the interlayer insulation film of thefirst layer and the interlayer insulation film of the second layer atonce, the aspect ratio becomes large, and the high resistance of theplug becomes conspicuous as a problem.

Therefore, while the plug diameter is reduced, the wire HL1 to becomethe source wire or the drain wire is formed on the interlayer insulationfilm of the first layer. By doing this, even if the plug diameter isreduced, since the wire HL1 is formed on the interlayer insulation filmof the first layer, it is possible to lower the aspect ratio of the plugPLG1, so that the high resistance of plug PLG1 is suppressed. In otherwords, the wire HL1 is provided on the interlayer insulation film of thefirst layer without forming the plug penetrating both of the interlayerinsulation film of the first layer and the interlayer insulation film ofthe second layer at once, whereby the plug PLG1 penetrating only theinterlayer insulation film of the first layer can be formed. Further, inorder to lower the aspect ratio of the plug PLG1, the interlayerinsulation film of the first layer is made thin. Furthermore, the wirewidth of the wire HL1 formed on the interlayer insulation film of thefirst layer is made thick, and the wire HL1 formed on the interlayerinsulation film of the first layer and a wire formed on the interlayerinsulation film of the second layer are connected by a plurality ofplugs, and thereby lowering the resistance of the plugs and the wires.In other words, since a gate length (gate width) of the gate electrode10 b of the high voltage resistant MISFET is as comparatively large asapproximately 2 μm to 3 μm, the wire HL1 is formed on the interlayerinsulation film of the first layer so as to be planarly overlapped withthe gate electrode 10 b of the high voltage resistant MISFET.

However, in the case where the wire HL1 is formed on the interlayerinsulation film of the first layer so as to be planalry overlapped withthe gate electrode 10 b of the high voltage resistant MISFET, voltageresistance failures occur between the gate electrode 10 b of the highvoltage resistant MISFET and the wire HL1 constituting the source wireor the drain wire. As causes of the voltage resistance failures, thereare the fact that the film thickness of the interlayer insulation filmof the first layer is made thin, and the fact that in the high voltageresistant MISFET, as mentioned above, the gate electrode 10 b runs ontothe electric field relaxing insulation region 3 protruding from thesemiconductor substrate 1S, and further, the fact that the filmthickness of the gate insulation film 8 is thick. Accordingly, it isthought that a distance between the wire HL1 and the gate electrode ofthe high voltage resistant MISFET that are overlapped planarly becomesshort, so that the voltage resistance failures occur. Further, in thehigh voltage resistant MISFET, the fact that the drive voltage is ascomparatively high as 20 V to 30 V is thought to be one of the causes.

Therefore, in the present embodiment, the wire HL1 to become the sourcewire and the drain wire are formed on the interlayer insulation film ofthe first layer, and the wires HL1 are arranged so that the wires HL1and the gate electrode 10 b of the high voltage resistant MISFET shouldnot be overlapped planarly. With this structure, first, even if thesemiconductor chip that is an LCD driver is miniaturized, the aspectratio of the plug PLG1 connecting the source region or the drain regionof the high voltage resistant MISFET and the wire HL1 can be made small.In other words, since the wires HL1 are formed on the interlayerinsulation film of the first layer, it is possible to form the plug PLG1penetrating only the interlayer insulation film of the first layerwithout forming a plug penetrating both the interlayer insulation filmof the first layer and the interlayer insulation film of the secondlayer at once. Accordingly, even if the diameter of the plug PLG1 isreduced, it is possible to restrain the aspect ratio of the plug PLG1from becoming large.

Furthermore, as shown in FIG. 2, the wires HL1 formed on the interlayerinsulation film of the first layer are arranged so that the wires HL1and the gate electrode 10 b of the high voltage resistant MISFET shouldnot be overlapped planarly. With this structure, since the wire HL1 isnot formed immediately over the gate electrode 10 b of the high voltageresistant MISFET, even if the interlayer insulation film of the firstlayer is made thin, it is possible to make large a distance between thewire HL1 and the gate electrode 10 b. Therefore, it is possible tosecure the voltage resistance between the gate electrode 10 b of thehigh voltage resistant MISFET and the wire HL1 becoming the source wireor the drain wire. In other words, according to the present embodiment,it is possible to obtain remarkable effects to restrain the highresistance of the plug due to miniaturization of the semiconductordevice, and to improve the voltage resistance failures between the gateelectrode of the high voltage resistant MISFET and the wires.

For example, the high voltage resistant MISFET has a structure in whichvoltage resistance failures between the wire (source wire or drain wire)HL1 formed on the interlayer insulation film of the first layer and thegate electrode 10 b easily occur due to the thin film thickness of theinterlayer insulation film of the first layer, the thick film thicknessof the gate insulation film, existence of the electric field relaxinginsulation region, and the high voltage of the drive voltage. However,by arranging the wires HL1 formed on the interlayer insulation film ofthe first layer so that the wires HL1 and the gate electrode 10 b shouldnot be overlapped planarly, it is possible to form the wires HL1 on theinterlayer insulation film of the first layer, and to make large thedistance between the wires HL1 and the gate electrode 10 b. Therefore,even if the LCD driver is miniaturized, it is possible to obtainremarkable effects to restrain the high resistance of the plug, and toimprove the voltage resistance failures between the gate electrode ofthe high voltage resistant MISFET and the wires.

In addition, the wires HL1 formed on the interlayer insulation film ofthe first layer, and the gate electrode 10 b are arranged not to beoverlapped planarly, and whereby the following effect is obtained. Thatis, since, the interlayer insulation film of the first layer on whichthe wires HL1 are arranged is made thin, the wire HL1 and the channelregion that is an interface between the gate insulation film of the highvoltage resistant MISFET and the semiconductor substrate 1S becomeclose. In the case where the wires HL1 are arranged to be overlappedwith the gate electrode 10 b planarly, the wires HL1 are overlappedplanarly with the channel region of the high voltage resistant MISFET.At this moment, if a high voltage is applied to the wires HL1, there isa possibility that the wires HL1 function as a gate electrode since theinterlayer insulation film of the first layer is made thin. In otherwords, when the wires HL1 have a region that is overlapped with thechannel region planarly, and a distance between the wires HL1 and thechannel region becomes short, the channel region overlapped planarlywith the wires HL1 is inverted by the voltage applied to the wires HL1.Then, the region that is overlapped planarly with the wires HL1 in theentire channel region becomes an inverted state. For this reason, theregion that is overlapped planarly with the wires HL1 in the channelregion is inverted even when the high voltage resistant MISFET is off,whereby a distance of the channel region that is not substantiallyinverted is made short. Accordingly, a problem in which the voltageresistance between the source region and the drain region lowers occurs.

However, in the present embodiment, the wires HL1 are arranged not to beoverlapped with the gate electrode 10 b planarly. For this reason, thewires HL1 are arranged not to be overlapped planarly with the channelregion formed immediately under the gate electrode 10 b. Therefore, itis possible to restrain the wires HL1 from functioning as a gateelectrode. In other words, according to the present embodiment, it ispossible to obtain effects to prevent an occurrence of a parasiticMISFET due to the wires HL1, and to restrain the voltage resistancelowering between the source region and the drain region.

FIG. 3 is a plan view showing the high voltage resistant MISFETformation region shown in FIG. 2 viewed from above. The cross sectioncut at the A-A line in FIG. 3 corresponds to the high voltage resistantMISFET formation regions in FIG. 2. As shown in FIG. 3, at both sides ofthe gate electrode 10 b, high voltage resistant high concentrationimpurity diffusion regions 14 to become the source region or the drainregion are formed, and between the high voltage resistant highconcentration impurity diffusion regions 14 and the gate electrode 10 b,electric field relaxing insulation regions 3 are formed. Over the highvoltage resistant MISFET configured in this manner, wires are formed viathe interlayer insulation film of the first layer (not shown). Inconcrete, over the high voltage resistant high concentration impuritydiffusion regions 14 to become the source region or the drain region,the wires HL1 are formed via plugs (first plug or second plug) PLG1. Asseen in FIG. 3, the wires HL1 are arranged not to be overlapped with thegate electrode 10 b planarly, and there is a distance between the gateelectrode 10 b and the wires HL1. Therefore, it is understood that thevoltage resistance between the gate electrode 10 b and the wires HL1 issecured.

On the other hand, a gate wire GL is connected to the gate electrode 10b via a plug (third plug) PLG1. This gate wire GL is formed with a wireof the same layer as that of the wires HL1 configuring a source wire ora drain wire. In other words, the gate wire GL is formed on theinterlayer insulation film of the first layer. As shown in FIG. 3, thisgate wire GL is arranged to have a region that is overlapped with thegate electrode 10 b planarly. In other words, the gate wire GL is to beelectrically connected to the gate electrode 10 b via the plug (thirdplug) PLG1, and accordingly, a problem of the voltage resistance betweenthe gate electrode 10 b and the gate wire GL does not occur. In thepresent embodiment, a purpose is to secure the voltage resistancebetween the wires formed on the interlayer insulation film of the firstlayer and the gate electrode 10 b. The problem of the voltage resistancewith respect to the gate electrode 10 b occurs in the source wireconnected electrically to the source region of the high voltageresistant MISFET and the drain wire connected electrically to the drainregion of the high voltage resistant MISFET from among the wires formedin the interlayer insulation film of the first layer. That is, it ischaracteristic that the gate electrode 10 b and the wires HL1 that arethe source wires or the drain wires are not overlapped planarly, and thegate wire GL connected electrically to the gate electrode 10 b may beoverlapped with the gate electrode 10 b planarly.

Herein, in the present embodiment, it is characteristic that the wiresHL1 formed on the interlayer insulation film of the first layer and thegate electrode 10 b of the high voltage resistant MISFET are notoverlapped planarly. At this moment, in other words, the wires HL1formed in the interlayer insulation film of the first layer can becalled wires of the lowest layer. However, in the case where wires arenot formed in the interlayer insulation film of the first layer, butformed in the interlayer insulation film of the second layer, wiresformed in the interlayer insulation film of this second layer may becalled wires of the lowest layer. Further, as for the interlayerinsulation film of the second layer, since wires are not formed in theinterlayer insulation film of the first layer, a combination of theinterlayer insulation film of the first layer and the interlayerinsulation film of the second layer may be called one interlayerinsulation film. Therefore, a certain definition is necessary to specifythe wire HL1 to become the object in the present embodiment.

This definition will be explained. In the present embodiment, there is aproblem caused by thinning the interlayer insulation film of the firstlayer. The voltage resistance between the wires HL1 formed over aninterlayer insulation film of the first layer and the gate electrode 10b becomes a problem by thinning this interlayer insulation film of thefirst layer. Therefore, the wire HL1 formed in the interlayer insulationfilm of the first layer is defined as follows.

As shown in FIG. 2, when a distance from the interface between thesemiconductor substrate 1S and the gate insulation film 8 to the upperportion of the gate electrode 10 b is defined as a, and a distance fromthe upper portion of the gate electrode 10 b to the upper portion of theinterlayer insulation film on which the wire HL1 is formed is defined asb, the wire HL1 having a relation of a>b is defined as the objectivewire in the present embodiment. That is, as the premise of the problemof the voltage resistance failures between the wire HL1 and the gateelectrode 10 b, attention is paid to a point that the interlayerinsulation film of the first layer is thinned, and a point that the gateinsulation film 8 of the high voltage resistant MISFET is thick and thegate electrode 10 b runs onto the electric field relaxing insulationregions 3. Therefore, it becomes possible to clearly define that a wirein which the voltage resistance failures occur between the gateelectrode 10 b and the wire is the wire HL1 arranged at the position ofa >b.

The fact that, in the high voltage resistant MISFET, the relation of a>bis established is concretely explained by numerical value examples.First, among the interlayer insulation films, a film thickness of thesilicon nitride film 16 is approximately 50 nm, and a film thickness ofsilicon oxide film 17 is approximately 500 nm. A film thickness of thegate insulation film 8 of the high voltage resistant MISFET isapproximately 80 nm, and a film thickness of the gate electrode 10 b isapproximately 250 nm. Therefore, the distance “a” from the interfacebetween the semiconductor substrate 1S and the gate insulation film 8 tothe upper portion of the gate electrode 10 b becomes approximately 330nm (80 nm+250 nm). On the other hand, the distance “b” from the upperportion of the gate electrode 10 b to the upper portion of theinterlayer insulation film on which the wire HL1 is formed becomesapproximately 220 nm (550 nm-330 nm). Therefore, it is understood thatthe relation of a>b is established. Further, since the electric fieldrelaxing insulation regions 3 protrude approximately 10 nm to 20 nm fromthe semiconductor substrate 1S, it is understood that the relation ofa>b is further satisfied. Thus, in the present embodiment, the voltageresistance between the gate electrode 10 b and the wire HL1 becomes theproblem, and as for this voltage resistance problem, it is clarifiedthat the wire in which a position relation between the wire HL1 and thehigh voltage resistant MISFET is a >b causes the problem. Therefore, asfor wires formed on the interlayer insulation films of the second layerand further upper layers which are not shown in FIG. 2, the relation ofa>b is not established, so that they are not objectives of the presentembodiment. In other words, as for the wires formed on the interlayerinsulation films of the second layer and further upper layers, thevoltage resistance failure does not become the problem because thedistance from the gate electrode 10 b of the high voltage resistantMISFET to the wire is sufficient. For this reason, there is no anyproblem even if the wires formed on the interlayer insulation films ofthe second layer and further upper layers (source wire and drain wire)are arranged to be overlapped with the gate electrode 10 b planarly. Byarranging the wires formed on the interlayer insulation films of thesecond layer and further upper layers to be overlapped with the gateelectrode 10 b planarly, it is possible to efficiently arrange thewires. In particular, in the high voltage resistant MISFET, since thegate length of the gate electrode 10 b is as wide as 2 μm to 3 μm, it isuseful to arrange the wires formed on the interlayer insulation films ofthe second layer and further upper layers to be overlapped with gateelectrode 10 b planarly.

Next, a wiring structure on the low voltage resistant MISFET will beexplained. As shown in FIG. 2, an interlayer insulation film of a firstlayer is formed over the low voltage resistant MISFET. In concrete, theinterlayer insulation film of the first layer is formed with a stackedfilm of a silicon nitride film 16 and a silicon oxide film 17. In theinterlayer insulation film of the first layer made of the siliconnitride film 16 and the silicon oxide film 17, a plug PLG1 penetratingthis interlayer insulation film and reaching the source region of thelow voltage resistant MISFET, and a plug PLG1 penetrating thisinterlayer insulation film and reaching the drain region of the lowvoltage resistant MISFET are formed. On the interlayer insulation filmof the first layer on which the plug PLG1 is formed, wires (source wiresand drain wires) LL1 are formed. Meanwhile, the wires LL1 are formed onthe interlayer insulation film of the first layer, but an interlayerinsulation film of the second layer and an interlayer insulation film ofthe third layer are further formed over the interlayer insulation filmof the first layer including these wires LL1, and wires are formed onthe respective layers. In other words, multilayer wirings are formedover the low voltage resistant MISFET, but in FIG. 2, only the wires LL1of the first layer are shown.

Herein, in the low voltage resistant MISFET, different from the highvoltage resistant MISFET, the wires LL1 of the first layer are arrangedto be overlapped with the gate electrode 10 a of the low voltageresistant MISFET planarly. In other words, in the low voltage resistantMISFET, the voltage resistance between the wires LL1 of the first layerand the gate electrode 10 a does not become a problem, which differsfrom the high voltage resistant MISFET.

This is because in the low voltage resistant MISFET, a film thickness ofthe gate insulation film 7 is thin, and since the electric fieldrelaxing insulation regions 3 are not formed, the gate electrode 10 adoes not run onto the electric field relaxing insulation regions 3.Furthermore, a drive voltage of the low voltage resistant MISFET isapproximately 5 V to 6 V, and accordingly, the voltage resistance issecured more easily than in the high voltage resistant MISFET whosedrive voltage is 20 V to 30 V. Therefore, the wires (source wires anddrain wires) LL1 formed on the interlayer insulation film of the firstlayer and the gate electrode 10 a may be overlapped planarly. For thisreason, since the gate length of the gate electrode 10 a of the lowvoltage resistant MISFET is approximately 160 nm, it is possible toutilize a space over this gate electrode 10 a effectively.

Furthermore, as a factor to secure the voltage resistance in the lowvoltage resistant MISFET, there is a fact that when a distance from theinterface between the semiconductor substrate 1S and the gate insulationfilm 7 to the upper portion of the gate electrode 10 a is defined as“c”, and a distance from the upper portion of the gate electrode 10 a tothe upper portion of the interlayer insulation film on which the wiresLL1 are formed is defined “d”, a relation c<d is established. In otherwords, the relation (a>b) established in the high voltage resistantMISFET is not established in the low voltage resistant MISFET, and as aresult of securing a distance between the gate electrode 10 a and thewires LL1, the voltage resistance failures between the gate electrode 10a and the wires LL1 do not become a problem in the low voltage resistantMISFET.

Explanations will be made by numerical value examples in concrete. Forexample, among the interlayer insulation films, a film thickness of thesilicon nitride film 16 is approximately 50 nm, and a film thickness ofthe silicon oxide film 17 is approximately 500 nm. A film thickness ofthe gate insulation film 7 of the low voltage resistant MISFET isapproximately 13 nm, and a film thickness of the gate electrode 10 a isapproximately 250 nm. Therefore, the distance “c” from the interfacebetween the semiconductor substrate 1S and the gate insulation film 7 tothe upper portion of the gate electrode 10 a becomes approximately 263nm (13 nm+250 nm). On the other hand, the distance “d” from the upperportion of the gate electrode 10 a to the upper portion of theinterlayer insulation film on which the wires LL1 are formed becomesapproximately 287 nm (550 nm-263 nm). Therefore, it is understood thatthe relation of c<d is established. In other words, in the low voltageresistant MISFET, the distance “d” from the upper portion of the gateelectrode 10 a to the wires LL1 is larger than the distance “c” from thelower portion of the gate insulation film 7 to the upper portion of thegate electrode 10 a, and the drive voltage is low, which is differentfrom the high voltage resistant MISFET. Accordingly, even if there is aregion where the gate electrode 10 a and the wires LL1 are overlappedplanarly, the voltage resistance failure does not occur.

As mentioned above, in the present embodiment, it is characteristic thatin the high voltage resistant MISFET formation regions, the wires HL1 tobecome the source wires and the drain wires are formed on the interlayerinsulation film of the first layer, and the wires HL1 are arranged sothat the wires HL1 and the gate electrode 10 b of the high voltageresistant MISFET should not be overlapped planarly. Whereby, it ispossible to obtain remarkable effects to restrain the high resistance ofthe plug due to miniaturization of the LCD driver, and to improve thevoltage resistance failure between the gate electrode of the highvoltage resistant MISFET and the wires.

The LCD driver (semiconductor device) according to the presentembodiment is configured as mentioned above, and hereinafter, a methodof manufacturing the same will be explained with reference to thedrawings.

First, a semiconductor substrate 1S made of silicon single crystal towhich p-type impurities such as boron (B) and the like are introduced isprepared. At this moment, the semiconductor substrate 1S is in a stateof a semiconductor wafer having a substantially disk shape. As shown inFIG. 4, element isolation regions 2 that isolate the low voltageresistant MISFET formation region and the high voltage resistant MISFETformation region of the semiconductor substrate 1S are formed. Theelement isolation regions 2 are provided so that elements do notinterfere with each other. The element isolation regions 2 may be formedby use of, for example, the local oxidation of silicon (LOCOS) method orthe shallow trench isolation (STI) method. For example, with the STImethod, the element isolation regions 2 are formed as follow. In otherwords, element isolation trenches are formed in the semiconductorsubstrate 1S by use of photolithography technique and etching technique.And a silicon oxide film is formed on the semiconductor substrate 1S soas to fill the element isolation trenches, thereafter, an unnecessarysilicon oxide film formed on semiconductor substrate 1S is removed byuse of CMP: chemical mechanical polishing method. Whereby, it ispossible to form the element isolation regions 2 in which the siliconoxide film is filled only in the element isolation trenches.

In the present embodiment, in the step of forming the element isolationregions 2, the electric field relaxing insulation regions 3 are alsoformed. The electric field relaxing insulation regions 3 are formed inthe same manner as the element isolation regions 2, and for example,they are formed by the STI method or the local oxidation of siliconmethod (LOCOS method). The electric field relaxing insulation regions 3are formed in the high voltage resistant MISFET formation region. Inparticular, since the electric field relaxing insulation regions 3 areformed in the high voltage resistant MISFET formation region, occupancyof the element isolation regions 2 and the electric field relaxinginsulation regions 3 becomes high. For this reason, for example, whenthe element isolation regions 2 and the electric field relaxinginsulation regions 3 are formed by the STI method, the element isolationregions 2 and the electric field relaxing insulation regions 3 tend toprotrude from the surface of semiconductor substrate 1S in the highvoltage resistant MISFET formation region. In other words, the elementisolation region 2 and the electric field relaxing insulation regions 3are configured so as to protrude, for example, 10 nm to 20 nm from thesurface of semiconductor substrate 1S. As mentioned later, in the highvoltage resistant MISFET, since the end portion of the gate electrode isformed on the electric field relaxing insulation regions 3, they areformed so as to run onto the protruding electric field relaxinginsulation regions 3. In particular, in the local oxidation of siliconmethod (LOCOS method), a selective oxide film is formed so as to swellfrom the surface of semiconductor substrate 1S, so that quantity inwhich the gate electrode runs onto the region 3 becomes large.

Subsequently, as shown in FIG. 5, impurities are introduced into activeregions isolated by the element isolation regions 2 to form a p-typewell 4. The p-type well 4 is formed, for example, by introducing p-typeimpurities such as boron and the like into the semiconductor substrate1S by the ion implantation method. This p-type well 4 is a well for thehigh voltage resistant MISFET, but it is formed in the high voltageresistant MISFET formation region and the low voltage resistant MISFETformation region. Then, a semiconductor region (not shown) for formingthe channel is formed in the surface region of the p-type well 4. Thesemiconductor region for forming the channel is formed to adjust thethreshold voltage to form the channel. In the present embodiment, thep-type wells 4 in the high voltage resistant MISFET formation region andthe low voltage resistant MISFET formation region are formed in a sameprocess, but it can be formed in separate processes. In that case, it ispossible to form an impurity concentration to be introduced into thehigh voltage resistant MISFET formation region and an impurityconcentration to be introduced into the low voltage resistant MISFETformation region, under optimal conditions respectively.

Next, as shown in FIG. 6, a p-type well 5 is formed in the low voltageresistant MISFET formation region. The p-type well 5 is formed, forexample, by introducing p-type impurities such as boron and the likeinto the semiconductor substrate 1S by the ion implantation method. Thisp-type well 5 is a well for the low voltage resistant MISFET.Thereafter, a pair of high voltage resistant low concentration impuritydiffusion regions 6 is formed in the high voltage resistant MISFETformation region. This high voltage resistant low concentration impuritydiffusion region 6 is a n-type semiconductor region, and it is formed byintroducing n-type impurities such as phosphor (P) and arsenic (As) andthe like into the semiconductor substrate 1S by the ion implantationmethod. The high voltage resistant low concentration impurity diffusionregion 6 is formed to contain the electric field relaxing insulationregion 3.

Thereafter, as shown in FIG. 7, a gate insulation film is formed on thesemiconductor substrate 1S. At this moment, in the low voltage resistantMISFET formation region, a thin gate insulation film 7 is formed, and inthe high voltage resistant MISFET formation region, a thick gateinsulation film 8 is formed. For example, a film thickness of the gateinsulation film 7 to be formed in the low voltage resistant MISFETformation region is approximately 13 nm, and a film thickness of thegate insulation film 8 to be formed in the high voltage resistant MISFETformation region is approximately 80 nm. In order to form the gateinsulation films of the different film thickness depending on theregions as mentioned-above, for example, after the thick gate insulationfilm 8 is formed on the semiconductor substrate 1S, the high voltageresistant MISFET formation region is masked with a resist film. Byetching with this resist film as a mask, the film thickness of the gateinsulation film 8 on the exposed low voltage resistant MISFET formationregion is reduced, and therefore, the thin gate insulation film 7 can beformed. In addition, the thin gate insulation film 7 is first formed onthe whole semiconductor substrate 1S, and a resist film is formed in thelow voltage resistant MISFET formation region. By forming the thick gateinsulation film 8 on the exposed high voltage resistant MISFET formationregion, the thin gate insulation film 7 can be formed in the low voltageresistant MISFET formation region and the thick gate insulation film 8can be formed in the high voltage resistant MISFET formation region. Theend portions of the gate insulation film 8 formed in the high voltageresistant MISFET formation region are formed so as to run onto theelectric field relaxing insulation regions 3.

The gate insulation films 7 and 8 are formed with, for example, asilicon oxide film, and can be formed by, for example, the thermaloxidation method. However, the gate insulation films 7 and 8 are notlimited to the silicon oxide film, but various changes may be made. Forexample, the gate insulation films 7 and 8 may be formed with a siliconoxide nitride film (SiON). In other words, a structure in which nitrogenis segregated on the interface between the gate insulation film 7 or 8and the semiconductor substrate 1S may be made. The silicon oxidenitride film has higher effects to suppress an occurrence of theinterface levels in the film and to reduce electronic traps incomparison with the silicon oxide film. Therefore, it is possible toimprove hot carrier resistance of the gate insulation films 7 and 8, andimprove the insulation resistance. In addition, the silicon oxidenitride film is hard to let impurities go through in comparison with thesilicon oxide film. For this reason, by using the silicon oxide nitridefilm for the gate insulation films 7 and 8, it is possible to restrainchange in the threshold voltage caused by diffusing the impurities ofthe gate electrode to the side of the semiconductor substrate 1S. Inorder to form the silicon oxide nitride film, for example, thesemiconductor substrate 1S may be subjected to heat treatment in anatmosphere including nitrogen such as NO, NO₂ or NH₃. In addition, thegate insulation films 7 and 8 made of silicon oxide film are formed onthe surface of the semiconductor substrate 1S and then are subjected tothe heat treatment in an atmosphere including nitrogen, and nitrogen ismade to be segregated on the interface between the gate insulation film7 or 8 and the semiconductor substrate 1S, so that the same effect maybe obtained.

In addition, for example, the gate insulation films 7 and 8 may beformed with a highly dielectric constant film having a higher dielectricconstant than that of the silicon oxide film. Conventionally, from theviewpoints of the high insulation resistance, and excellent electricaland physical stability of the interface between the silicon and thesilicon oxide and so forth, the silicon oxide film is used as the gateinsulation films 7 and 8. However, along with miniaturizing of elements,there has been a demand for an extremely thin film thickness of the gateinsulation films 7 and 8. When such an extremely thin silicon oxide filmis used as the gate insulation films 7 and 8, electrons flowing throughthe channel of the MISFET can tunnel through a barrier formed with thesilicon oxide film and flow into the gate electrode, that is, aso-called tunnel current occurs.

Therefore, high dielectric films that can increase a physical filmthickness with a same capacity by use of material whose dielectricconstant is higher than that of the silicon oxide have come to be used.Since the physical film thicknesses can be increased even with a samecapacity by the high dielectric films, it is possible to reduce a leakelectric current.

For example, as the high dielectric film, a hafnium oxide film (HfO₂film) that is one of the hafnium oxides is used, but in the place of thehafnium oxide film, other hafnium based insulation films such as ahafnium aluminate film, an HfON film (hafnium oxinitride film), an HfSiOfilm (a hafnium silicate film), an HfSiON film (hafnium siliconoxinitride film), an HfAlO film and the like may be used. Furthermore,it is possible to use hafnium based insulation films in which oxidessuch as tantalum oxide, niobium oxide, titanium oxide, zirconium oxide,lanthanum oxide, yttrium oxide and the like are introduced into thesehafnium based insulation films. Since the hafnium based insulation filmshave, as with the hafnium oxide film, the dielectric constants higherthan those of the silicon oxide film and the silicon oxide nitride film,it is possible to obtain the same effect as in the case of using thehafnium oxide film.

Subsequently, as shown in FIG. 8, a polysilicon film is formed on thegate insulation films 7 and 8. The polysilicon film 9 may be formed, forexample, by use of the CVD method. By use of the photolithographytechnique and the ion implantation method, n-type impurities such asphosphorus, arsenic, or the like is introduced into the polysilicon film9.

Next, by etching using a patterned resist film as a mask, thepolysilicon film 9 is processed, so that a gate electrode 10 a is formedin the low voltage resistant MISFET formation region, and a gateelectrode 10 b is formed in the high voltage resistant MISFET formationregion. The gate length of the gate electrode 10 a is, for example,approximately 160 nm, and the gate length of the gate electrode 10 b is,for example, approximately 2 μm to 3 μm. The end portions of the gateelectrode 10 b formed in the high voltage resistant MISFET formationregion is formed to run onto the electric field relaxing insulationregions 3 via the gate insulation film 8.

Herein, in the gate electrodes 10 a and 10 b, n-type impurities areintroduced into the polysilicon film 9. For this reason, it is possibleto make work function values of the gate electrodes 10 a and 10 b to bethe value close to the conductive band (4.15 eV) of the silicon, andaccordingly, it is possible to reduce the threshold voltage of the lowvoltage resistant MISFET and the high voltage resistant MISFET that isan n-channel type MISFET.

Subsequently, as shown in FIG. 9, a shallow low voltage resistant lowconcentration impurity diffusion region 11 aligned to the gate electrode10 a of the low voltage resistant MISFET is formed by use of thephotolithography technique and the ion implantation method. The shallowlow voltage resistant low concentration impurity diffusion region 11 isan n-type semiconductor region.

As shown in FIG. 10, a silicon oxide film is formed over thesemiconductor substrate 1S. The silicon oxide film may be formed by, forexample, the CVD method. By performing anisotropic etching of thesilicon oxide film, side walls 12 are formed on side walls of the gateelectrodes 10 a and 10 b. The side walls 12 are formed with asingle-layered film of a silicon oxide film, but the present inventionis not limited to this, for example, the side walls 12 formed with astacked film of a silicon nitride film and a silicon oxide film may beformed.

Next, as shown in FIG. 11, by use of the photolithography technique andthe ion implantation method, deep low voltage resistant highconcentration impurity diffusion regions 13 aligned to the side walls 12are formed in the low voltage resistant MISFET formation region. Thedeep low voltage resistant high concentration impurity diffusion region13 is an n-type semiconductor region. The source region or the drainregion of the low voltage resistant MISFET are formed with the deep lowvoltage resistant high concentration impurity diffusion regions 13 andthe shallow low voltage resistant low concentration impurity diffusionregions ii. By forming the source region and the drain region with theshallow low voltage resistant low concentration impurity diffusionregions 11 and the deep low voltage resistant high concentrationimpurity diffusion regions 13 in this manner, it is possible to make thesource region and the drain region have a Lightly Doped Drain (LDD)structure.

The ion implantation of n-type impurities to form the low voltageresistant high concentration impurity diffusion regions 13 is performedalso to the high voltage MISFET formation regions at the same time, andwhereby the high voltage resistant high concentration impurity diffusionregions 14 are formed. The high voltage resistant high concentrationimpurity diffusion regions 14 are also an n-type semiconductor region,and they are formed outside the electric field relaxing insulationregions 3 so as to be contained in the high voltage resistant lowconcentration impurity diffusion regions 6. In the high voltageresistant MISFET, the source region or the drain region is formed withthe high voltage resistant high concentration impurity diffusion regions14 and the high voltage resistant low concentration impurity diffusionregions 6.

After the low voltage resistant high concentration impurity diffusionregion 13 and the high voltage resistant high concentration impuritydiffusion region 14 are formed as described above, a heat treatment ataround 1000C.° is performed to them. Whereby, the impurities introducedare activated.

Subsequently, as shown in FIG. 12, a cobalt film is formed over thesemiconductor substrate 1S. At this moment, the cobalt film is formed tocontact with the gate electrodes 10 a and 10 b directly. In the samemanner, the cobalt film contacts with the deep low voltage resistanthigh concentration impurity diffusion regions 13 and the high voltageresistant high concentration impurity diffusion regions 14 directly.

The cobalt film may be formed by, for example, the sputtering method.After the cobalt film is formed, by performing a heat treatment, thepolysilicon film 9 constituting the gate electrodes 10 a and 10 b andthe cobalt film are reacted to form a cobalt silicide film 15. Whereby,the gate electrodes 10 a and 10 b become a stacked structure of thepolysilicon film 9 and the cobalt silicide film 15. The cobalt silicidefilm 15 is formed for lowering a resistant of the gate electrodes 10 aand 10 b. In the same manner, by the heat treatment mentioned above, thesilicon and the cobalt film react also on the surface of the low voltageresistant high concentration impurity diffusion regions 13 and the highvoltage resistant high concentration impurity diffusion regions 14, sothat the cobalt silicide film 15 is formed. Accordingly, it is possibleto realize the low resistance in the low voltage resistant highconcentration impurity diffusion regions 13 and the high voltageresistant high concentration impurity diffusion regions 14.

Then, an unreacted cobalt film is removed from the semiconductorsubstrate 1S. In the present embodiment, the cobalt silicide film 15 isformed, but in the place of the cobalt silicide film 15, for example, anickel silicide film or a titanium silicide film may be formed. In thismanner, the low voltage resistant MISFET and the high voltage resistantMISFET can be formed over the semiconductor substrate 1S.

Next, a wiring step will be explained. First, as shown in FIG. 13, asilicon nitride film 16 to become an interlayer insulation film isformed over the main surface of the semiconductor substrate 1S, and ansilicon oxide film 17 is formed on this silicon nitride film 16.Whereby, the interlayer insulation film of the first layer becomes astacked film of the silicon nitride film 16 and the silicon oxide film17. The silicon nitride film 16 may be formed by, for example, the CVDmethod, and the silicon oxide film 17 may be formed by, for example, theCVD method using tetra ethyl ortho silicate (TEOS) as its raw material.At this moment, a film thickness of the silicon nitride film 16 isapproximately 50 nm, and a film thickness of the silicon oxide film 17is approximately 1100 nm.

Thereafter, as shown in FIG. 14, a surface of the silicon oxide film 17is planarized by, for example, the Chemical Mechanical Polishing (CMP)method. In this process, the film thickness of the silicon oxide film 17decreases and becomes, for example, approximately 550 nm. In thismanner, the film thickness of the silicon oxide film 17 is thinned.

Subsequently, as shown in FIG. 15, contact halls CNT1 are formed in thesilicon oxide film 17 by use of the photolithography technique and theetching technique. The contact halls CN=1 penetrate the interlayerinsulation film of the first layer made of the silicon oxide film 17 andthe silicon nitride film 16 and reach the semiconductor substrate 1S. Inconcrete, the contact halls CNT1 are formed in the high voltageresistant MISFET formation region and the low voltage resistant MISFETformation region. In the high voltage resistant MISFET formation region,a contact hall (first contact hall) CNT1 reaching the source region(cobalt silicide film 15) is formed, and another contact hall (secondcontact hall) CNT1 reaching the drain region (cobalt silicide film 15)is formed. Incidentally, although not shown in FIG. 15, a contact hallreaching the gate electrode 10 b is also formed. In the same manner, inthe low voltage resistant MISFET formation region, a contact hall CNT1reaching the source region (cobalt silicide film 15) is formed, and acontact hall CNT1 reaching the drain region (cobalt silicide film 15) isformed. In addition, although not shown in figure, a contact hallreaching the gate electrode 10 a is also formed.

Next, as shown in FIG. 16, a titanium/titanium nitride film 18 a isformed on the silicon oxide film 17 including a bottom surface and aninside wall of the contact hall CNT1. The titanium/titanium nitride film18 a is configured with a stacked film of a titanium film and a titaniumnitride film, and may be formed by use of, for example, the sputteringmethod. This titanium/titanium nitride film 18 a has so-called barriercharacteristics to prevent, for example, tungsten that is a filmmaterial to be buried in the later process from diffusing into thesilicon. Thereafter, a tungsten film 18 b is formed on the entiresurface of the main surface of the semiconductor substrate 1S to fill upthe contact halls CNT1. This tungsten film 18 b may be formed by, forexample, the CVD method.

Subsequently, as shown in FIG. 17, an unnecessary titanium/titaniumnitride film 18 a and tungsten film 18 b formed on the silicon oxidefilm 17 are removed by, for example, the CMP method, and thetitanium/titanium nitride film 18 a and the tungsten film 18 b are leftonly in the contact halls CNT1, and whereby, the plug PLG1 can beformed. By the CMP polishing at this time, the silicon oxide film 17 ispolished. In concrete, the film thickness of the silicon oxide film 17before the CMP polishing is approximately 550 nm, meanwhile, the filmthickness of the silicon oxide film 17 after the CMP polishing isapproximately 500 nm.

In the high voltage resistant MISFET formation region, the plug (firstplug) PLG1 electrically connected to the source region of the highvoltage resistant MISFET and the plug (second plug) PLG1 electricallyconnected to the drain region of the high voltage resistant MISFET areformed. Although not shown in the figure, a plug (third plug)electrically connected to the gate electrode 10 b is also formed. In thesame manner, in the low voltage resistant MISFET formation region, theplug PLG1 electrically connected to the source region of the low voltageresistant MISFET and the plug PLG1 electrically connected to the drainregion of the low voltage resistant MISFET are formed. Meanwhile,although not shown in the figure, a plug electrically connected to thegate electrode 10 a is also formed.

Next, as shown in FIG. 18, a titanium/titanium nitride film 19 a, analuminum film 19 b containing copper, a titanium/titanium nitride film19 c are sequentially formed on the silicon oxide film 17 and the plugPLG1. These films may be formed by use of, for example, the sputteringmethod. Thereafter, these films are patterned by use of thephotolithography technique and the etching technique to form wires HL1and wires LL1. Through these processes, the wires HL1 and the wires LL1may be formed on the interlayer insulation film of the first layer.

Since the wires HL1 and the wires LL1 may be formed on the interlayerinsulation film of the first layer, it is possible to make small theaspect ratio of the plug PLG1 connected to the wire HL1 and the wireLL1. Therefore, even if a diameter of the plug PLG1 is reduced and theminiaturization of the chip region is carried out, it is possible torestrain the high resistance of the plug PLG1. Furthermore, in thepresent embodiment, the wire (source wire) HL1 connected to the sourceregion of the high voltage resistant MISFET via the plug PLG1 and thewire (drain wire) HL1 connected to the drain region of the high voltageresistant MISFET via the plug PLG1 are arranged as follows. In otherwords, the wires HL1 arranged on the interlayer insulation film of thefirst layer and the gate electrode 10 b should not be overlappedplanarly. Whereby, since the wires HL1 are not formed immediately overthe gate electrode 10 b of the high voltage resistant MISFET, it ispossible to keep the distance between the wires HL1 and the gateelectrode 10 b away even if the interlayer insulation film of the firstlayer is made thin. Therefore, it is possible to secure the voltageresistance between the gate electrode 10 b of the high voltage resistantMISFET and the wires HL1 to become the source wire or the drain wire. Inother words, according to the present embodiment, it is possible toobtain remarkable effects to restrain the high resistance of the plugdue to the miniaturization of the semiconductor device, and to improvethe voltage resistance failures between the gate electrode of the highvoltage resistant MISFET and the wires.

In addition, although not shown in the figure, the gate wireelectrically connected to the gate electrode 10 b is formed on theinterlayer insulation film of the first layer. In other words, the gatewire is formed by the same layer as that of the wires HL1 constitutingthe source wire or the drain wire. The gate wire is electricallyconnected to the gate electrode 10 b, so that the voltage resistancebetween the gate wire and the gate electrode 10 b does not become aproblem. For this reason, the gate wire is arranged to be overlappedwith the gate electrode 10 b planarly.

On the other hand, in the low voltage resistant MISFET formation region,wires LL1 are formed on the interlayer insulation film of the firstlayer. Since the voltage resistance between the wires LL1 and the gateelectrode 10 a does not become the problem in the low voltage resistantMISFET, a wire width of the wire LL1 is made wide to be overlapped withthe gate electrode 10 a planarly. Whereby, it is possible to utilize aspace over the gate electrode 10 a effectively and to realize the lowresistance of the wire LL1.

Next, as shown in FIG. 19, a silicon oxide film 20 that is an interlayerinsulation film of the second layer is formed on the interlayerinsulation film of the first layer on which the wires HL1 and wires LL1are formed. In the same manner as the process mentioned above, plugsPLG2 are formed in the silicon oxide film 20. The plugs PLG2 areconnected to the wires HL1 and wires LL1. Wires HL2 and the wires LL2are formed on the silicon oxide film 20 in which the plugs PLG2 areformed. Herein, since the wires HL1 and the wires HL2 are connected by aplurality of rows of plugs PLG2, it is possible to reduce the wireresistance and the plug resistance. In the same manner, the wires LL1and the wires LL2 are connected by the plurality of rows of plugs PLG2,so that it is possible to reduce the wire resistance and the plugresistance.

In the high voltage resistant MISFET formation region, the wires HL2formed on the silicon oxide film 20 that is the interlayer insulationfilm of the second layer may be arranged to be overlapped with the gateelectrode 10 b planarly. this is because a distance between the wiresHL2 arranged on the interlayer insulation film of the second layer andthe gate electrode 10 b are sufficiently away in comparison with adistance between the wires HL1 arranged on the interlayer insulationfilm of the first layer and the gate electrode 10 b, and so the voltageresistance between the wires HL2 and the gate electrode 10 b does notbecome a problem. For this reason, by effectively utilizing a space overthe gate electrode 10 b having the gate length of approximately 2 μm to3 μm, it is possible to realize the low resistance of the wire HL2 bywidening the wire width of the wire HL2. On the interlayer insulationfilm of the second layer, a plurality of wires may be arranged in aregion overlapped planarly with the gate electrode 10 b.

Furthermore, multilayer wirings are formed by forming wires on an upperlayer of the wires HL2 and the wires LL2. A bump electrode is formed onthe highest layer of the multilayer wirings. A process of forming thisbump electrode will be explained.

FIG. 20 shows a silicon oxide film 21 formed over the multilayerwirings, and pads PAD are formed on the silicon oxide film 21. A lowerlayer structure of the silicon oxide film 21 is omitted, but in thelower layer of the silicon oxide film 21, the low voltage resistantMISFET, the high voltage resistant MISFET and multilayer wirings shownin FIG. 19 are formed.

As shown in FIG. 20, for example, the silicon oxide film 21 is formed.The silicon oxide film 21 may be formed, for example, by use of the CVDmethod. Then, a titanium/titanium nitride film, an aluminum film and atitanium/titanium nitride film are stacked and formed on the siliconoxide film 21. Thereafter, by use of the photolithography technique andthe etching technique, the stacked film is patterned. By this patterningprocess, pads PAD can be formed on the silicon oxide film 21.

Subsequently, as shown in FIG. 21, a surface protective film 22 isformed on the silicon oxide film 21 on which the pads PAD are formed.The surface protective film 22 may be formed with, for example, asilicon nitride film, and may be formed by the CVD method. Next, by useof the photolithography technique and the etching technique, an openingportion is formed in the surface protective film 22. This openingportion is formed on the pads PAD and exposes a surface of the pads PAD.

Next, as shown in FIG. 22, on the surface protective film 22 includingthe opening portion, an Under Bump Metal (UBM) film 23 is formed. TheUBM film 23 may be formed, for example, by use of the sputtering method,and formed with a single layer film or a stacked film of, for example, atitanium film, a nickel film, a palladium film, a titanium tungstenalloy film, a titanium nitride film or a gold film. Herein, the UBM film23 has a function to improve adhesive property between the bumpelectrodes and the pads PAD or the surface protective film 22, and afunction as an electrode. In addition, the UBM film 23 has a barrierfunction to restrain or prevent metallic elements of a conductive filmto be formed in the next process from moving to the multilayer wiringside, and on the contrary, prevent metallic elements constituting themultilayer wirings from moving to the conductive film side.

Subsequently, as shown in FIG. 23, after a resist film RES is appliedonto the UBM film 23, this resist film RES is subjected to anexposure/development processing to pattern the film. The patterning isperformed so that the resist film RES should not be left in the bumpelectrode formation region. Then, as shown in FIG. 24, as a conductivefilm 24, for example, a gold film is formed by the plating method.Thereafter, as shown in FIG. 25, the patterned resist film RES and theUBM film 23 covered with the resist film RES are removed, and whereby abump electrode BMP composed of the conductive film 24 and the UBM film23 is formed.

Next, a semiconductor substrate in a semiconductor wafer state is diced,and whereby singulated semiconductor chips CHP are obtained. Thesingulated semiconductor chip CHP is such a chip as shown in FIG. 1.Thereafter, the semiconductor chips CHP obtained by dividing thesemiconductor substrate into pieces are mounted on a glass substrate.

Next, a state where the semiconductor chip CHP that is an LCD driver isadhered onto a package substrate and mounted thereon is shown. FIG. 26shows a case where the semiconductor chip CHP is mounted on a glasssubstrate 30 a (COG: Chip On Glass). As shown in FIG. 26, a glasssubstrate 30 b is mounted on the glass substrate 30 a, so that a displayportion of an LCD is formed. And on the glass substrate 30 a at thevicinity of the display portion of the LCD, the semiconductor chip CHPthat is the LCD driver is mounted. A bump electrode BMP is formed in thesemiconductor chip CHP, and the bump electrode BMP and a terminal formedon the glass substrate 30 a are connected via an anisotropic conductivefilm 32. In addition, the glass substrate 30 a and a flexible printedcircuit 31 are also connected by the anisotropic conductive film 32. Inthe semiconductor chip CHP mounted on the glass substrate 30 a in thismanner, the bump electrode BMP for output is electrically connected tothe display portion of the LCD, and the bump electrode BMP for input isconnected to the flexible print substrate 31.

FIG. 27 is a figure showing an entire structure of the LCD. As shown inFIG. 27, a display portion 33 of the LCD is formed on the glasssubstrate, and an image is displayed on this display portion 33. Thesemiconductor chip CHP that is the LCD driver is mounted on the glasssubstrate at the vicinity of the display portion 33. The flexible printsubstrate 31 is mounted at the vicinity of the semiconductor chip CHP,and the semiconductor chip CHP that is the LCD driver is mounted betweenthe flexible print substrate 31 and the display portion 33 of the LCD.In this manner, it is possible to mount the semiconductor chip CHP onthe glass substrate. Through the processes, it is possible to mount theLCD driver on the glass substrate and manufacture the LCD.

Second Embodiment

One of the characteristics of the first embodiment lies in, as shown inFIG. 28, a point where the wires HL1 to become the source wire and thedrain wire are formed on the insulation film (silicon oxide film 17) ofthe first layer, and the wires HL1 are arranged so that the wires HL1and the gate electrode 10 b of the high voltage resistant MISFET shouldnot be overlapped planarly. In FIG. 28, a distance “e” of an interval inwhich the gate electrode 10 b of the high voltage resistant MISFET andthe wires HL1 are not overlapped planarly is shown, and in a secondembodiment, specific numerical value examples of this distance “e” willbe explained.

FIG. 28 is a cross sectional view showing the high voltage resistantMISFET and the low voltage resistant MISFET, and it is a figure similarto FIG. 2. However, in FIG. 28, the distance “e” of the interval wherethe gate electrode 10 b and the wires HL of the high voltage resistantMISFET are not overlapped planarly, and a diameter “z” of the plug PLG1are shown.

As shown in FIG. 28, the gate electrode 10 b of the high voltageresistant MISFET and the wire HL are separated by only a planar distance“e”, but it is necessary to determine this distance “e” in considerationof dimensional errors of a pattern and a gap of patterns formed by thephotolithography process. For example, even when a sufficient distance“e” is set to secure the voltage resistance between the gate electrode10 b and the wires HL in a design process, it is thought that there is acase where the gate electrode 10 b and wires HL1 may be processed to beoverlapped planarly due to dimensional errors in the processing of gateelectrode 10 b and the wires HL or matching gaps between the gateelectrode 10 b and the plug PLG1 and between the plug PLG1 and the wiresHL1 and the like. In this case, it is not possible to secure the voltageresistance between the gate electrode 10 b and the wires HL1.

Therefore, it is necessary to set the distance “e” so as to secure thedistance “e,” of the interval where the gate electrode 10 b and thewires HL1 are not overlapped planarly, even if the dimensional errors ofthe pattern or the matching gaps of the patterns occur in theabove-mentioned photolithography process.

FIG. 29 is a table concretely showing the dimensional errors of thepattern and the matching gaps between patterns in the photolithographyprocess. For example, in FIG. 29, it is understood that the dimensionalerror (unevenness) of the gate electrode 10 b becomes 40 nm at themaximum when the gate electrode 10 b is formed by the photolithographyprocess. Furthermore, the matching gap (stack gap, unevenness) of theplug PLG1 to the gate electrode 10 b becomes 40 nm at the maximum. Inthe same manner, the dimensional error of the wires HL1 is 40 nm at themaximum, and the stack gap of the wires HL1 to the plug PLG1 is 70 nm atthe maximum. Therefore, in a case when these dimensional errors and thestack gaps work all in a direction where the interval in which the gateelectrode 10 b and the wires HL1 are not overlapped planarly is madeshort, an error in which the distance “e” is made shortest is generated

In other words, in the case when the distance “e” is 190 nm (40 nm+40nm+40 nm+70 nm) or less, in some sizes of the dimensional errors of thepattern and the stack gaps in the photolithography process, the gateelectrode 10 b and the wires HL1 are formed to have a region which isoverlapped planarly. As a result, a situation where the voltageresistance between the gate electrode 10 b and the wires HL1 cannot besecured occurs. In other words, in the case when the distance “e” is 190nm or more, it is possible to prevent an occurrence of the region wherethe gate electrode 10 b and the wires HL1 are overlapped planarly, evenif the dimensional errors of the pattern and the stack gaps of thepattern in the photolithography process are caused by any cases. Fromthis fact, by making the distance “e” 190 nm or more, it is possible toprevent the gate electrode 10 b and the wires HL1 from being overlappedplanarly even if the dimensional errors of the pattern and the stackgaps of the patterns in the photolithography process are caused. As aresult, it is possible to securely improve the voltage resistancebetween the gate electrode 10 b and the wires HL1 and to realizereliability improvement of the semiconductor device.

In the above-mentioned description, the example where the distance “e”,at which the gate electrode 10 b and the wires HL1 are not overlappedplanarly, is made larger than the value (190 nm) obtained by simplyadding the dimensional errors of the pattern and the stack gaps of thepatterns in the photolithography process is shown. However, it isthought that there is a low probability of all the dimensional errors ofpatterns and the stack gaps between patterns occur in the direction tomake the distance “e” shorter, and therefore, there may be anothermethod to take the square sum as a method to evaluate the distance “e”.In other words, the dimensional errors of the pattern and the stack gapsbetween patterns in the photolithography process are evaluated by thesquare sum. In this case, the distance “e” becomes √(40×40+40×40+40×40+70×70)=98 nm, and by making the distance “e” morethan 98 nm (approximately 100 nm), it is possible to sufficientlyprevent the gate electrode 10 b and the wires HL1 from being overlappedplanarly.

Third Embodiment

In the first embodiment, it is characteristic that the wires HL1 formedon the interlayer insulation film of the first layer (silicon oxide film17) and the gate electrode 10 b of the high voltage resistant MISFETshown in FIG. 28 are arranged not to be overlapped planarly. In otherwords, in the first embodiment, attention is paid to a problem caused bythinning the interlayer insulation film of the first layer, and is paidto the fact that the voltage resistance between the wires HL1 formed inthe interlayer insulation film of the first layer and the gate electrode10 b becomes the problem caused by thinning the insulation film of thefirst layer. At this moment, in the first embodiment, it isquantitatively defined that the interlayer insulation film of the firstlayer is thinned.

In concrete, as shown in FIG. 28, when the distance from the interfacebetween the semiconductor substrate 1S and the gate insulation film 8 tothe upper portion of the gate electrode 10 b is defined as “a”, and thedistance from the upper portion of the gate electrode 10 b to the upperportion of the interlayer insulation film on which the wire HL1 isformed is defined as “b”, the wire HL1 in which the relation a>b issatisfied is defined as the objective wire in the first embodiment. Thatis, as a premise of the problem of the voltage resistance failurebetween the wire HL1 and the gate electrode 10 b, attention is paid tothe point that the interlayer insulation film of the first layer isthinned, and the point that the gate insulation film 8 of the highvoltage resistant MISFET is thick and the gate electrode 10 b runs ontothe electric field relaxing insulation area 3. Whereby, it becomespossible to clearly define that the wire HL, which is arranged at theposition of a>b, causes the problem of the voltage resistance failurewith the gate electrode 10 b.

In a third embodiment, another expression of the above-mentionedcondition a>b will be explained. First, as mentioned above, when thedistance from the interface between the semiconductor substrate 1S andthe gate insulation film 8 to the upper portion of the gate electrode 10b is defined as “a” and the distance from the upper portion of the gateelectrode 10 b to the upper portion of the interlayer insulation film onwhich the wire HL1 is formed is defined as “b”, a condition in which therelation a>b is established is a prior condition of the presentinvention. Herein, as another condition, there is a relation between adiameter “z” of the plug PLG1 and a thickness “f” (not shown) of theinterlayer insulation film (silicon oxide film 17+silicon nitride film16) (f=a+b). In other words, the plug PLG1 is formed to penetrate theinterlayer insulation film, and from the view point to make embeddingcharacteristic of the plug PLG1 preferable, it is necessary to make anaspect ratio a specified value or less. Herein, the aspect ratio is aquantity f/z expressed by the thickness “f” of the interlayer insulationfilm and the diameter “z” of the plug PLG1. For example, when thisaspect ratio becomes large, the embedding characteristic becomes worseby forming the plug PLG1 of a small diameter in a thick interlayerinsulation film. In other words, from the viewpoint of making theembedding characteristic of the plug PLG1 preferable, it is necessary tomake the aspect ratio a specified value or below. In concrete, forexample, this condition may be expressed by a condition of f/z<5. Inother words, when the thickness “f” of the interlayer insulation filmand the diameter “z” of the plug PLG1 are determined so that the aspectratio f/z is 5 or less, it is possible to prevent the embeddingcharacteristic of the plug PLG1 from deteriorating.

Herein, the thickness f of the interlayer insulation film is expressedby f=a+b, and from this expression, a=f−b is obtained. When this isassigned to a>b, f>2b is obtained. On the other hand, from therelational expression of the aspect ratio f/z<5, f<5z is obtained.Accordingly, from the two relational expressions f<5z and f>2b, therelation 2b<5z is obtained. When this 2b<5z is solved by b, it becomesthat b<2.5z. From the above, it is understood that the condition a >bmay be replaced by the condition b<2.5z by use of the thickness of theinterlayer insulation film f=a+b and the relational expression of theaspect ratio f/z<5. By words, when the distance from the upper portionof the gate electrode 10 b to the upper portion of the interlayerinsulation film on which the wires HL1 are formed is defined as “b”, andthe diameter of the plug PLG1 is defined as “z”, the condition where therelation of b<2.5z is established may be replaced by a condition thatthe distance “b” from the upper portion of the gate electrode 10 b tothe upper portion of the interlayer insulation film on which the wiresHL1 are arranged is smaller than 2.5 times of the diameter “z” of theplug PLG1. In other words, as for the feature of the present invention,in the third embodiment, when the distance “b” from the upper portion ofthe gate electrode 10 b to the upper portion of the interlayerinsulation film on which the wires HL1 are arranged is smaller than 2.5times of the diameter “z” of the plug PLG1, the gate electrode 10 b andthe wires HL1 should be arranged so as not to be overlapped planarly.

Incidentally, the diameter of the plug PLG1 is defined as “z”, and whenthe diameter of the plug PLG1 is same in the whole of the plug PLG1,there is no problem. But actually, the diameter at the surface of theinterlayer insulation film (silicon oxide film 17) is largest, and thediameter is formed so as to become smaller toward the bottom portion ofthe plug PLG1. In this case, there is a problem that at which depth thediameter “z” of the plug PLG1 is taken. But in the third embodiment, thediameter at the bottom portion of the plug PLG1 is defined as “z”.

Fourth Embodiment

In the first embodiment, the case where the present invention is appliedto the high voltage resistant MISFET is explained, but in a fourthembodiment, a case where the present invention is applied to aresistance element will be explained. In other words, in the LCD driver,in addition to the low voltage resistant MISFET and the high voltageresistant MISFET, a plurality of resistance elements constitutingcircuits are formed. Among these resistance elements, there areresistances to which a high voltage is applied in the same manner as inthe high voltage resistant MISFET. Therefore, the voltage resistancebecomes a problem in the resistance elements using the high voltage inthe same manner as the high voltage resistant MISFET.

FIG. 30 is a plan view showing a resistance element in the fourthembodiment. In FIG. 30, a gate insulation film 8 is formed on thesemiconductor substrate 1S, and a polysilicon film (conductive film) 40to become a resistance element is formed on this gate insulation film 8.Wires 43 are connected to this polysilicon film 40 to become theresistance element by plugs (fourth plugs) 42. On the other hand, wire44 not connected to the resistance element is also formed.

The feature of the fourth embodiment is that among the wires 43 and thewires 44 formed on the polysilicon film 40 to become the resistanceelement, the wire 44 to which an electric potential different from thatof the polysilicon film 40 is applied is arranged not to be overlappedwith the polysilicon film 40 planarly. In other words, since the wire 43electrically connected directly to the polysilicon film 40 via the plug42 is conductive, the problem of the voltage resistance does not occurwith the polysilicon film 40. From this fact, as shown in FIG. 30, thepolysilicon film 40 and the wire 43 are arranged to be overlappedplanarly. In contrast, in the wire 44 not electrically connecteddirectly to the polysilicon film 40 via the plug 42 and to which anelectric potential different from that of the polysilicon film 40 isapplied, there is a case where a high potential difference is generatedbetween the polysilicon film 40 and the wire 44. In this case, thevoltage resistance becomes a problem between the polysilicon film 40 andthe wire 44. Therefore, for the wire 44 not electrically connecteddirectly to the polysilicon film 40 via the plug 42, the polysiliconfilm 40 to become a resistance element is arranged so as not to beoverlapped with the wire 44 planarly. By this structure, even if a highvoltage is applied to between the polysilicon film 40 to become theresistance element and the wire 44, it is possible to secure the voltageresistance.

FIG. 31 is a cross sectional view at the B-B line in FIG. 30. In FIG.31, the resistance element formation region is formed to be adjacent tothe high voltage resistant MISFET formation region. Hereinafter, astructure of the resistance element formed in the resistance elementformation region will be explained. In FIG. 31, an element isolationregion 2 is formed over the semiconductor substrate 1S, and on thiselement isolation region 2, a film (referred to as gate insulation film8) having the same film thickness as that of the gate insulation film 8used for the high voltage resistant MISFET is formed. A polysilicon film40 is formed on this gate insulation film 8, and the polysilicon film 40is formed by use of the same film as that of the polysilicon filmconstituting the gate electrode 10 b of the high voltage resistantMISFET. The polysilicon film 40 functions as a resistance element. Onside walls of this polysilicon film 40, side walls 41 similar to theside walls 12 are formed by performing a process of forming the sidewalls 12 of the MISFET. Furthermore, in a part of the surface of thepolysilicon film 40, a cobalt silicide film 15 is formed.

An interlayer insulation film is formed so as to cover the polysiliconfilm 40. The interlayer insulation film is formed with a silicon nitridefilm 16 and a silicon oxide film 17. In the interlayer insulation film,a plug 42 penetrating the interlayer insulation film and reaching thecobalt silicide film 15 formed on the surface of the polysilicon film 40is formed, and a wire 43 electrically connected directly to this plug 42is formed on the interlayer insulation film. Since FIG. 31 shows thecross sectional view at the B-B line in FIG. 30, the wire 43electrically connected directly to the polysilicon film 42 via the plug42 is shown. In addition, it is shown in FIG. 30 that the feature of thefourth embodiment in which the wire 44 and the polysilicon film 40 arenot overlapped planarly.

Herein, the resistance element is formed by use of a process of formingthe high voltage resistant MISFET. In other words, for the gateinsulation film 8 formed over the element isolation region 2, the samefilm as that of gate insulation film 8 of the high voltage resistantMISFET is used, and for the polysilicon film 40 formed on the gateinsulation film 8, the same film as that of the polysilicon filmconstituting the gate electrode 10 b of the high voltage resistantMISFET is used. Therefore, a height of the resistance element becomessame as that of the high voltage resistant MISFET.

On the other hand, a thickness of the interlayer insulation film is thesame thickness in both regions of the high voltage resistant MISFETformation region and the resistance element formation region, and fromthe viewpoint of lowering the aspect ratio of the plug PLG1 in the highvoltage resistant MISFET as much as possible, the thickness of theinterlayer insulation film is made thin.

From this fact, in the high voltage resistant MISFET formation region,when the distance from the interface between the semiconductor substrate1S and the gate insulation film 8 to the upper portion of the gateelectrode 10 b is defined as “a”, and the distance from the upperportion of the gate electrode 10 b to the upper portion of theinterlayer insulation film on which the wires HL1 are formed is definedas “b”, the condition of a>b is established.

The polysilicon film 40 (resistance element) is formed on the gateinsulation film 8, and the polysilicon film 40 (resistance element) isformed with the same film as that of the polysilicon film constitutingthe gate electrode 10 b of the high voltage resistant MISFET. For thisreason, even in the resistance element formation region, a distance fromthe interface between the semiconductor substrate 1S and the gateinsulation film 8 to the upper portion of the polysilicon film becomessame as “a”, and a distance from the upper portion of the polysiliconfilm 40 to the upper portion of the interlayer insulation film on whichthe wire 43 and the wire 44 (refer to FIG. 30) are formed becomes sameas “b”. For this reason, in the resistance element formation region, thecondition of a>b is established.

From the above fact, in the resistance element, the film thickness ofthe interlayer insulation film existing between the polysilicon film 40and the wire 44 (not shown in FIG. 31) is thin, and as with the highvoltage resistant MISFET, the voltage resistance between the polysiliconfilm 40 and the wire 44 via the interlayer insulation film becomes aproblem. Therefore, as shown in FIG. 30, also in the resistance element,among the wire 43 and the wire 44 formed on the polysilicon film 40which is to be the resistance element, the wire 44 to which an electricpotential different from that of the polysilicon film 40 is applied isarranged not to be overlapped with polysilicon film 40 planarly. By thisstructure, even if the interlayer insulation film becomes thin, it ispossible to secure the voltage resistance between the polysilicon film40 and the wire 44.

Herein, as a method of lowering the height of the resistance element, itis thought that there may be the case where the polysilicon film 40constituting the resistance element is not formed on the thick gateinsulation film 8, but directly formed on the element isolation region2, or the case where the polysilicon film 40 is formed on the thin gateinsulation film of the low voltage resistant MISFET. In this case, sincethe height of the polysilicon film 40 constituting the resistanceelement is made low, the thickness of the interlayer insulation filmexisting between the polysilicon film 40 and the wire 44 can be madethick, and therefore, it is thought that the voltage resistance betweenthe polysilicon film 40 and the wire 44 can be improved.

However, in the fourth embodiment, the polysilicon film that is theresistance element is formed on the same film as that of the gateinsulation film 8 of the high voltage resistant MISFET for the followingreason. This reason will be explained with reference to the drawings.FIG. 32 and FIG. 33 are cross sectional views showing a process offorming a general element isolation region. For example, as shown inFIG. 32, an element isolation trench 2 a is formed in the semiconductorsubstrate 1S by use of the photolithography technique and the etchingtechnique. As shown in FIG. 33, after the silicon oxide film is formedto be filled in this element isolation trench 2 a, the silicon oxidefilm formed on the surface of the semiconductor substrate 1S is removedby the chemical mechanical polishing method (CMP). Accordingly, sincethe silicon oxide film can be left only in the element isolation trench2 a, it is possible to form the element isolation region 2 in which theelement isolation trench 2 a is filled with the silicon oxide film. FIG.32 and FIG. 33 are the formation process of the normal element isolationregion 2.

However, for example, as shown in FIG. 34, it is assumed that when theelement isolation trench 2 a is formed in the semiconductor substrate1S, a foreign matter 45 a attaches to an etching region of thesemiconductor substrate 1S. Then, the foreign matter 45 a becomes themask, and silicon formed under the foreign matter is left without beingetched. In other words, an etching remain 45 is formed under the foreignmatter 45 a as shown in FIG. 34. Thereafter, as shown in FIG. 35, whenthe element isolation trench 2 a is filled with the silicon oxide filmto form the element isolation region 2, the etching remain 45 is left.

Therefore, when the polysilicon film 40 to become the resistance elementis formed over the element isolation region 2 in which the etchingremain 45 is formed, since the etching remain 45 is formed with silicon,an inconvenience that the polysilicon film 40 and the semiconductorsubstrate 1S are shortcircuited via the etching remain 45 occurs. Thisinconvenience becomes conspicuous in the case where the polysilicon film40 is formed directly on the element isolation region 2, and as shown inFIG. 36, in the case where the polysilicon film 40 is formed via a thingate insulation film 7, since a high voltage is applied to thepolysilicon film 40, shortcircuit failures tend to be generated.

From this fact, as shown in FIG. 37, after the thick gate insulationfilm 8 is formed on the element isolation region 2, the polysilicon film40 is formed on this thick gate insulation film 8. By forming the thickgate insulation film 8 between the polysilicon film 40 that is theresistance element and the element isolation region 2, as shown in FIG.37, even if the etching remain 45 is generated in the element isolationregion 2, it is possible to largely reduce a possibility of theshortcircuit between the polysilicon film 40 and the semiconductorsubstrate 1S via the etching remain 45.

From the above-mentioned reasons, the polysilicon film 40 constitutingthe resistance element is formed on the same thick gate insulation film8 as the gate insulation film 8 of the high voltage resistant MISFET.For this reason, the polysilicon film 40 (resistance element) is formedon the gate insulation film 8, and the polysilicon film 40 (resistanceelement) is formed with the same film of the polysilicon filmconstituting the gate electrode 10 b of the high voltage resistantMISFET. Therefore, in the resistance element formation region, thedistance from the interface between the semiconductor substrate 1S andthe gate insulation film 8 to the upper portion of the polysilicon film40 is the same distance as “a”, and the distance from the upper portionof polysilicon film 40 to the upper portion of the interlayer insulationfilm on which the wire 43 and the wire 44 (refer to FIG. 30) are formedis the same distance as “b”. For this reason, also in the resistanceelement formation region, the condition of a>b is established.

However, in the fourth embodiment, among the wire 43 and the wire 44formed on the polysilicon film 40 to become the resistance element, thewire 44 to which an electric potential different from that of thepolysilicon film 40 is applied is arranged not to be overlapped withpolysilicon film 40 planarly, and therefore, even if the interlayerinsulation film is thin, it is possible to realize an remarkable effectto secure the voltage resistance between an polysilicon film 40 and thewire 44.

Fifth Embodiment

In the first embodiment, the process has been explained where after thelow voltage resistant MISFET and the high voltage resistant MISFET areformed, the interlayer insulation film is formed so as to cover the lowvoltage resistant MISFET and the high voltage resistant MISFET,thereafter, wires are formed on the interlayer insulation film. In afifth embodiment, the formation process of the interlayer insulationfilm will be explained in more details.

FIG. 38 is a cross sectional view showing a state where the low voltageresistant MISFET, the high voltage resistant MISFET, and the resistanceelement are formed over the semiconductor substrate 1S. In other words,in FIG. 38, in addition to the low voltage resistant MISFET and the highvoltage resistant MISFET, the resistance element is formed. Thisresistance element is formed by use of the process of forming the highvoltage resistant MISFET. As shown in FIG. 38, a silicon nitride film 16is formed so as to cover the low voltage resistant MISFET, the highvoltage resistant MISFET, and the resistance element. The siliconnitride film 16 may be formed by, for example, the CVD method.

Subsequently, as shown in FIG. 39, a silicon oxide film 50 is formed onthe silicon nitride film 16 formed over the semiconductor substrate 1S.This silicon oxide film 50 may be formed, for example, by the highdensity plasma CVD method using high density plasma. The high densityplasma is what gas is made into a plasma state at a high density by useof a high frequency electric field and a magnetic field. The highdensity plasma CVD method is a method in which gas introduced into achamber is made into a high density plasma state, and the high densityplasma is chemically reacted, and whereby a film is deposited on thesemiconductor substrate 1S. As the method of generating the high densityplasma, there are, for example, the induction coupled plasma (ICP) andthe electron cyclotron resonance (ECR) method and the like.

The induction coupled plasma is one kind of the high density plasmasused in the chemical vapor deposition method, and is plasma generated byactivating gas introduced into a chamber by high frequency coils. On theother hand, the electronic cyclotron resonance is a followingphenomenon. That is, when an electron receives the Lorentz force in amagnetic field, the electrons performs a cyclotron movement in which itgoes around on a plane perpendicular to the magnetic field. At thismoment, on the movement plane of the electron, an electric fieldmatching the go-around frequency is given, an energy resonance betweenthe cyclotron movement and the electric field occurs, and the electricfield energy is absorbed into the electron, so that a large energy issupplied to the electron. By use of this phenomenon, it is possible tomake various gases into high density plasma state.

The silicon oxide film 50 formed by the high density plasma CVD methodas above-mentioned is advantageous in that its embedding characteristicis excellent. Therefore, even in an element such as a memory cell of anStatic Random Access Memory (SRAM) in which an interval between the gateelectrodes is made narrow with a microminiaturized structure, it ispossible to make the embedding characteristic of the silicon oxide filmto the gate electrodes preferable by forming the silicon oxide film 50on the silicon nitride film 16 by the high density plasma CVD method. Inother words, in the semiconductor device to become the LCD driver, theSRAM is also mounted, and as for this SRAM, the distance between thegate electrodes become extremely narrow with the microminiaturizedstructure. For this reason, when the silicon oxide film is filled inbetween the gate electrodes by the CVD method by use of normal densityplasma, a space between the gate electrodes cannot be filledsufficiently, and “void space” is generated in the space between thegate electrodes. When the “void space” is generated between the gateelectrodes, a conductive film used to form plugs in a process mentionedlater enters into the inside of the “void space”, and a failure in whichadjacent plugs cause a shortcircuit via the conductive film entering inthe inside of the “void space”. Therefore, in the fifth embodiment, thesilicon oxide film 50 is formed on the silicon nitride film 16 by use ofthe high density plasma CVD method having preferable embeddingcharacteristic. By depositing the silicon oxide film 50 by use of thehigh density plasma CVD method in this manner, in elements of themicrominiaturized structure such as the SRAM, it is possible to improvethe embedding characteristic into the space between the gate electrodes.As a result, it is possible to restrain an occurrence of the “voidspace” and prevent the shortcircuit among adjacent plugs.

Next, as shown in FIG. 40, a silicon oxide film 51 is formed on thesilicon oxide film 50. The silicon oxide film 51 may be made, forexample, by use of the plasma CVD method in which tetra ethyl orthosilicate (TEOS) is used as raw material. In the plasma CVD method usingthe TEOS as the raw material, the normal density plasma lower than thedensity of the high density plasma CVD method mentioned-above is used.In the normal plasma CVD method using the TEOS as the raw material, filmthickness control characteristics of the silicon oxide film 51 ispreferable, and the silicon oxide film 51 is formed to increase the filmthickness of the interlayer insulation film.

Subsequently, as shown in FIG. 41, the surface of the silicon oxide film51 is planarized. In order to planarize the surface of the silicon oxidefilm 51, for example, the surface of the silicon oxide film 51 ispolished by the chemical mechanical polishing (CMP). In this process,there is a possibility that the film thickness of the silicon oxide film51 is made thin due to unevenness of a polishing amount by the CMP andthe like, and whereby the upper portion of the high voltage resistantMISFET and the upper portion of the resistance element may be exposed.

Therefore, as shown in FIG. 42, a silicon oxide film (cap insulationfilm) 52 is formed on the planarized silicon oxide film 51. This siliconoxide film 52 may be formed in the same manner as for the silicon oxidefilm 51, by use of the normal plasma CVD method using TEOS as rawmaterial.

Subsequently, as shown in FIG. 43, by use of the photolithographytechnique and the etching technique, contact holes are formed in theinterlayer insulation films (silicon oxide film 52, silicon oxide film51, silicon oxide film 50 and silicon nitride film 16). The contactholes penetrate the interlayer insulation films and reach thesemiconductor substrate 1S.

A titanium/titanium nitride film is formed on the interlayer insulationfilm including the bottom surface and the inside wall of the contacthole. The titanium/titanium nitride film is configured with a stackedfilm of the titanium film and the titanium nitride film, and may beformed, for example, by use of the sputtering method. Thereafter, atungsten film is formed over an entire surface of the main surface ofthe semiconductor substrate 1S to fill up the contact holes. Thistungsten film may be formed, for example, by use of the CVD method.

Next, an unnecessary titanium/titanium nitride film and tungsten filmformed on the interlayer insulation film are removed, for example, bythe CMP method, so that the titanium/titanium nitride film and thetungsten film are left only in the contact holes, and whereby plugs PLG1and plugs 42 can be formed.

Next, as shown in FIG. 44, a titanium/titanium nitride film, an aluminumfilm containing copper, a titanium/titanium nitride film are formedsequentially on the silicon oxide film 52 and the plugs PLG1. Thesefilms may be formed, for example, by use of the sputtering method.Subsequently, these films are patterned by use of the photolithographytechnique and the etching technique, and whereby wires HL1, wires LL1,wires 43 and wires 53 are formed. In this manner, it is possible to formthe wires HL1, the wires LL1, the wires 43 and the wires 53 on theinterlayer insulation film of the first layer.

Also in the fifth embodiment, as with the first embodiment, the wiresHL1 formed on the interlayer insulation film of the first layer and thegate electrode 10 b are arranged not to be overlapped planarly. Withthis structure, since the wires HL1 are not formed immediately over thegate electrode 10 b of the high voltage resistant MISFET, it is possibleto keep the distance between the wires HL1 and the gate electrode 10 baway even if the interlayer insulation film of the first layer is madethin. For this reason, it is possible to secure the voltage resistancebetween the gate electrode 10 b of the high voltage resistant MISFET andthe wires HL1 to become the source wire or the drain wire.

On the other hand, in the resistance element formation area, the wire 43electrically connected directly to the polysilicon film 40 to become theresistance element via the plug 42 is formed so as to be overlapped withthe polysilicon film 40 planarly. However, among the wire 43 and thewire 53 formed over the polysilicon film 40 to become the resistanceelement, the wire 53, which is not connected directly to the polysiliconfilm 40 via the plug 42 and to which an electric potential differentfrom that of the polysilicon film 40 is applied, is arranged not to beoverlapped with the polysilicon film 40 planarly, so that it is possibleto secure the voltage resistance between the polysilicon film 40 and thewire 53 even if the interlayer insulation film is made thin.

In the foregoing, the invention made by the inventors of the presentinvention has been concretely described based on the embodiments.However, it is needless to say that the present invention is not limitedto the foregoing embodiments and various modifications and alterationscan be made within the scope of the present invention.

In the above-mentioned embodiments, the example in which an n-channeltype MISFET is used as the low voltage resistance MISFET and the highvoltage resistant MISFET formed on the LCD driver, however, thetechnological ideas of the present embodiments may be also applied to acase when a p-channel type MISFET is used as the low voltage resistantMISFET and the high voltage resistant MISFET.

The present invention may be applied widely to the manufacturingindustry to manufacture semiconductor devices.

1. A semiconductor device comprising: (a1) a gate insulation film formedon a semiconductor substrate; (a2) a gate electrode formed on the gateinsulation film; (a3) a MISFET having a source region and a drain regionformed so as to align with the gate electrode; (b) an insulation filmformed over the MISFET; (c) a first plug penetrating the insulation filmand electrically connected to the source region; (d) a second plugpenetrating the insulation film and electrically connected to the drainregion; (e) a source wire formed over the insulation film andelectrically connected to the first plug; and (f) a drain wire formedover the insulation film and electrically connected to the second plug,wherein when a distance from an interface between the semiconductorsubstrate and the gate insulation film to an upper surface of the gateelectrode is defined as a, and a distance from the upper surface of thegate electrode to an upper surface of the insulation film on which thesource wire and the drain wire are formed is defined as b, a relation ofa>b is established, and the gate electrode and the source wire arearranged not to be overlapped planarly with each other, and the gateelectrode and the drain wire are arranged not to be overlapped planarlywith each other.
 2. The semiconductor device according to claim 1,wherein the source wire and the drain wire constitute a wiring layer ofthe lowest layer.
 3. The semiconductor device according to claim 1,wherein an electric field relaxing insulation region is formed in thesource region and the drain region.
 4. The semiconductor deviceaccording to claim 3, wherein an end portion of the gate electrode runsonto the electric field relaxing insulation region.
 5. The semiconductordevice according to claim 3, wherein the electric field relaxinginsulation region protrudes from the semiconductor substrate.
 6. Thesemiconductor device according to claim 3, wherein the electric fieldrelaxing insulation region is formed by embedding an insulation materialinto a trench formed in the semiconductor substrate.
 7. Thesemiconductor device according to claim 3, wherein the electric fieldrelaxing insulation region is formed by a selective oxidation method. 8.The semiconductor device according to claim 1, wherein the insulationfilm is formed with a stacked film of a silicon nitride film and asilicon oxide film.
 9. The semiconductor device according to claim 1,wherein a gate wire electrically connected to the gate electrode isformed with a wire of the same layer as that of the source wire and thedrain wire.
 10. The semiconductor device according to claim 9, whereinthe gate wire has a region overlapped with the gate electrode planarly.11. The semiconductor device according to claim 1, wherein a drivevoltage of the MISFET is 20 V or more.
 12. The semiconductor deviceaccording to claim 1, wherein the semiconductor device is an LCD driverused in a liquid crystal display device.
 13. A method of manufacturing asemiconductor device comprising the steps of: (a) forming an elementisolation region and an electric field relaxing insulation region in asemiconductor substrate; (b) forming a gate insulation film over thesemiconductor substrate; (c) forming a pair of low concentrationimpurity diffusion regions so that each of the impurity regions containsthe electric field relaxing insulation region; (d) forming a gateelectrode over the gate insulation film; (e) forming a side-wall on sidewalls of both sides of the gate electrode; (f) forming a pair of highconcentration impurity diffusion regions in a region contained in thepair of low concentration impurity diffusion regions and existingoutside the electric field relaxing insulation region, and forming asource region configured with one of the pair of low concentrationimpurity diffusion regions and one of the pair of high concentrationimpurity diffusion regions included therein, and a drain regionconfigured with the other one of the pair of low concentration impuritydiffusion regions and the other one of the pair of high concentrationimpurity diffusion regions included therein; (g) forming an insulationfilm so as to cover the gate electrode; (h) forming a first plugpenetrating the insulation film and reaching the source region, and asecond plug penetrating the insulation film and reaching the drainregion; and (i) forming a source wire connected to the first plug overthe insulation film, and a drain wire connected to the second plug overthe insulation film, wherein when a distance from an interface betweenthe semiconductor substrate and the gate insulation film to an upperportion of the gate electrode is defined as a, and a distance from theupper portion of the gate electrode to an upper surface of theinsulation film on which the source wire and the drain wire are formedis defined as b, a relation of a>b is established, and the gateelectrode and the source wire are formed not to be overlapped planarlywith each other, and the gate electrode and the drain wire are formednot to be overlapped planarly with each other.
 14. The method ofmanufacturing a semiconductor device according to claim 13, wherein thesource wire and the drain wire constitute a wiring layer of the lowestlayer.
 15. The method of manufacturing a semiconductor device accordingto claim 13, further comprising the step of: polishing a surface of theinsulation film to planarize the surface of the insulation film, afterthe step (g) and before the step (h).
 16. The method of manufacturing asemiconductor device according to claim 13, the step (h) includes thesteps of: (h1) forming a first contact hole reaching the source regionand a second contact hole reaching the drain region in the insulationfilm; (h2) forming a conductive film on the insulation film including aninside of the first contact hole and an inside of the second contacthole; and (h3) polishing the conductive film to remove the conductivefilm formed on the insulation film and also to leave the conductive filmin the inside of the first contact hole and the inside of the secondcontact hole, and thereby forming the first plug and the second plug.17. The method of manufacturing a semiconductor device according toclaim 13, wherein in the step (h), a third plug reaching the gateelectrode is formed, in the step (i), a gate wire connected to the thirdplug is formed with the same layer as that of the source wire and thedrain wire, and the gate electrode and the gate wire have a region wherethey are overlapped with each other planarly.
 18. The method ofmanufacturing a semiconductor device according to claim 13, wherein inthe step (g), a silicon nitride film is formed to cover the gateelectrode, an silicon oxide film is formed on the silicon nitride film,and whereby the insulation film is formed with a laminated film of thesilicon nitride film and the silicon oxide film.
 19. The method ofmanufacturing a semiconductor device according to claim 13, wherein inthe step (a), a trench is formed in the semiconductor substrate, aninsulation material is embedded into the trench, and whereby the elementisolation region and the electric field relaxing insulation region areformed.
 20. The method of manufacturing a semiconductor device accordingto claim 13, wherein in the step (d), the gate electrode is formed sothat an end portion of the gate electrode is formed over the electricfield relaxing insulation region.
 21. A semiconductor device comprising:(a1) a gate insulation film formed on a semiconductor substrate; (a2) agate electrode formed on the gate insulation film; (a3) a MISFET havinga source region and a drain region formed so as to align with the gateelectrode; (b) an insulation film formed over the MISFET; (c) a firstplug penetrating the insulation film and electrically connected to thesource region; (d) a second plug penetrating the insulation film andelectrically connected to the drain region; (e) a source wire formedover the insulation film and electrically connected to the first plug;and (f) a drain wire formed over the insulation film and electricallyconnected to the second plug, wherein an electric field relaxinginsulation region is formed in the source region and the drain region,an end portion of the gate electrode runs onto the electric fieldrelaxing insulation region, and the gate electrode and the source wireare arranged not to be overlapped planarly with each other, and the gateelectrode and the drain wire are arranged not to be overlapped planarlywith each other.
 22. The semiconductor device according to claim 1,wherein a distance in which the gate electrode and the source wire arenot overlapped planarly, or a distance in which the gate electrode andthe drain wire are not overlapped planarly is 100 nm or more.
 23. Asemiconductor device comprising: (a1) a gate insulation film formed on asemiconductor substrate; (a2) a gate electrode formed on the gateinsulation film; (a3) a MISFET having a source region and a drain regionformed so as to align with the gate electrode; (b) an insulation filmformed over the MISFET; (c) a first plug penetrating the insulation filmand electrically connected to the source region; (d) a second plugpenetrating the insulation film and electrically connected to the drainregion; (e) a source wire formed over the insulation film andelectrically connected to the first plug; and (f) a drain wire formedover the insulation film and electrically connected to the second plug,wherein when a diameter of the first plug and a diameter of the secondplug are defined as z, and a distance from an upper surface of the gateelectrode to an upper surface of the insulation film on which the sourcewire and the drain wire are formed is defined as b, a relation of b<2.5zis established, and the gate electrode and the source wire are arrangednot to be overlapped planarly with each other, and the gate electrodeand the drain wire are arranged not to be overlapped planarly with eachother.
 24. The semiconductor device according to claim 1, thesemiconductor substrate including a resistance element formation regiondifferent from a region where the MISFET is formed, wherein in theresistance element formation region, (g) an element isolation regionformed in the semiconductor substrate, (h) the gate insulation filmformed over the element isolation region, (i) a conductive film tobecome a resistance element formed over the gate insulation film, (j)the insulation film formed to cover the conductive film, (k) a fourthplug penetrating the insulation film and electrically connected to theconductive film, (l) a first wire formed over the insulation film andelectrically connected to the fourth plug, and (m) a second wire formedover the insulation film and to which an electric potential differentfrom that of the conductive film is applied, are formed, further, thefirst wire and the second wire are formed on a same layer, and the firstwire and the conductive film have a region where they are overlappedplanarly, meanwhile the second wire and the conductive film do not havea region where they are overlapped planarly.
 25. The method ofmanufacturing a semiconductor device according to claim 13, wherein thestep (g) further includes the steps of: (g1) forming a first insulationfilm to cover the gate electrode; (g2) forming a second insulation filmover the first insulation film; (g3) planarizing a surface of the secondinsulation film; and (g4) forming a cap insulation film over the secondinsulation film, and in order to form the first insulation film, plasmaused in forming the first insulation film at the step (g1) is higherdensity plasma than plasma used in forming the second insulation film atthe step (g2), and the insulation film includes the first insulationfilm, the second insulation film, and the cap insulation film.